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Stojanova J, Brown JD, Reuter SE, Marriott DJE. Very high linezolid clearance in a critically ill patient: A case report suggesting a novel metabolic induction mechanism. Int J Antimicrob Agents 2024; 63:107170. [PMID: 38604388 DOI: 10.1016/j.ijantimicag.2024.107170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/13/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024]
Affiliation(s)
- Jana Stojanova
- Department of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Sydney, NSW, Australia; School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, NSW, Australia.
| | - Jeremy D Brown
- Clinical Microbiology and Infectious Diseases Department, St. Vincent's Hospital, Sydney, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Deborah J E Marriott
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, NSW, Australia; Clinical Microbiology and Infectious Diseases Department, St. Vincent's Hospital, Sydney, NSW, Australia
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Alonge M, Coller JK, Reuter SE, Jesudason S, Sallustio BC. Determining Plasma Tacrolimus Concentrations Using High-Performance LC-MS/MS in Renal Transplant Recipients. Ther Drug Monit 2024; 46:49-56. [PMID: 38193880 DOI: 10.1097/ftd.0000000000001135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 06/07/2023] [Indexed: 01/10/2024]
Abstract
BACKGROUND Whole-blood therapeutic drug monitoring of tacrolimus is conducted to maintain tacrolimus concentrations within a safe and effective range. Changes in hematocrit cause variability in blood concentrations of tacrolimus because it is highly bound to erythrocytes. Measuring plasma concentrations may eliminate this variability; however, current methods have limitations owing to the use of cross-reactive immunoassays, plasma separation at nonbiological temperatures, and lack of clinical validation. This study aimed to develop and validate a clinically applicable method to measure plasma tacrolimus concentrations in renal transplant recipients and to examine the concentration differences between genotypic CYP3A5 expressors and nonexpressors. METHODS Plasma tacrolimus concentrations were measured in 9 stable renal transplant recipients who were genotypic CYP3A5 expressors or nonexpressors. Tacrolimus was extracted from plasma using solid-phase extraction, and liquid chromatography-tandem mass spectrometry was used for detection and quantitation. RESULTS This assay was sensitive, selective, and linear between 100 and 5000 ng/L, with intraassay and interassay imprecision and inaccuracy <10% and <5% respectively. The extraction recovery of tacrolimus and ascomycin was 74%. Matrix ion suppression effects were 31.5% and 35% with overall recovery of 50.6% and 48.3% for tacrolimus and ascomycin, respectively. Whole-blood concentrations accounted for approximately 46% of the variation in plasma concentrations in CYP3A5 expressors and nonexpressors. No difference in dose-adjusted whole-blood and plasma concentrations was observed between CYP3A5 expressors and nonexpressors. CONCLUSIONS This assay is clinically applicable with excellent performance and demonstrated that tacrolimus plasma concentrations highly correlated with whole-blood concentrations.
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Affiliation(s)
- Mirabel Alonge
- Department of Clinical Pharmacology, The Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, Woodville South, Australia
- Discipline of Pharmacology, School of Biomedicine, The University of Adelaide, Adelaide, Australia
| | - Janet K Coller
- Discipline of Pharmacology, School of Biomedicine, The University of Adelaide, Adelaide, Australia
| | - Stephanie E Reuter
- Clinical and Health Sciences, University of South Australia, Adelaide, Australia; and
| | - Shilpanjali Jesudason
- Central and Northern Adelaide Renal and Transplantation Service, Royal Adelaide Hospital, Adelaide, Australia
| | - Benedetta C Sallustio
- Discipline of Pharmacology, School of Biomedicine, The University of Adelaide, Adelaide, Australia
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Yang JJ, Brett J, Sordo A, Reuter SE, Stocker SL, Day RO, Roberts DM, Carland JE. The Influence of a Therapeutic Drug Monitoring Service on Vancomycin-Associated Nephrotoxicity. J Clin Pharmacol 2024; 64:19-29. [PMID: 37779493 DOI: 10.1002/jcph.2363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/29/2023] [Indexed: 10/03/2023]
Abstract
Vancomycin's widespread use as the mainstay antibiotic against methicillin-resistant Staphylococcus aureus infections is complicated by its narrow therapeutic index. Therapeutic drug monitoring using area under the concentration-time curve (AUC)-guided dosing is recommended to optimize therapy and prevent vancomycin-associated nephrotoxicity (VAN). In 2018, a consultative therapeutic drug monitoring Advisory Service (the Service) was piloted at an Australian hospital to enable AUC-guided vancomycin dosing. This study sought to compare the incidence of VAN pre- and post-Service implementation. A 4-year retrospective observational study of intravenous vancomycin therapy (greater than 48 hours) in adults (aged 18 years or older), spanning 3 years before and 1-year after implementation of the Service was undertaken. Nephrotoxicity was defined as an increase in serum creatinine concentrations of 26.5 μmol/L or greater or 50% or more from baseline, on 2 or more consecutive days. Univariate analysis was performed to compare patients before and after implementation, and with and without VAN. Independent factors associated with VAN were identified using a multivariate model. In total, 971 courses of vancomycin therapy, administered to 781 patients, were included: 764 courses (603 patients) before implementation and 207 courses (163 patients) after implementation. The incidence of VAN decreased by 5% after Service implementation (15% before implementation vs 10% after implementation; P = .075). Independent factors associated with VAN were sepsis, heart failure, solid-organ transplant, concomitant piperacillin-tazobactam, and average vancomycin AUC during therapy. In conclusion, there was a nonsignificant trend toward a reduced incidence of VAN after the Service. Larger prospective studies are needed to confirm the efficacy of the Service.
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Affiliation(s)
- Jennifer J Yang
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
| | - Jonathan Brett
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
| | - Anna Sordo
- School of Public Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, Australia
| | - Sophie L Stocker
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Richard O Day
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
| | - Darren M Roberts
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
- Drug Health Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Jane E Carland
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, NSW, Australia
- School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW Sydney, Australia
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4
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Tan MS, Patel BK, Roughead EE, Ward M, Reuter SE, Roberts G, Andrade AQ. Opportunities for clinical decision support targeting medication safety in remote primary care management of chronic kidney disease: A qualitative study in Northern Australia. J Telemed Telecare 2023:1357633X231204545. [PMID: 37822219 DOI: 10.1177/1357633x231204545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
INTRODUCTION This study aimed to identify opportunities for clinical decision support targeting medication safety in remote primary care, by investigating the relationship between clinical workflows, health system priorities, cognitive tasks, and reasoning processes in the context of medicines used in people with chronic kidney disease (CKD). METHODS This qualitative study involved one-on-one, semistructured interviews. The participants were healthcare professionals employed in a clinical or managerial capacity with clinical work experience in a remote health setting for at least 1 year. RESULTS Twenty-five clinicians were interviewed. Of these, four were rural medical practitioners, nine were remote area nurses, eight were Aboriginal health practitioners, and four were pharmacists. Four major themes were identified from the interviews: (1) the need for a clinical decision support system to support a sustainable remote health workforce, as clinicians were "constantly stretched" and problems may "fall through the cracks"; (2) reliance on digital health technologies, as medical staff are often not physically available and clinicians-on-duty usually "flick an email and give a call so that I can actually talk it through to our GP"; (3) knowledge gaps, as "it takes a lot of mental space" to know each patient's renal function and their medication history, and clinicians believe "mistakes can be made"; and (4) multiple risk factors impacting CKD management, including clinical, social and behavioural determinants. CONCLUSIONS The high prevalence of CKD and reliance on digital health systems in remote primary health settings can make a clinical decision support system valuable for supporting clinicians who may not have extensive experience in managing medicines for people with CKD.
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Affiliation(s)
- Madeleine Sa Tan
- Faculty of Health, Charles Darwin University, Darwin, NT, Australia
| | - Bhavini K Patel
- Medicines Management Unit, Department of Health, Northern Territory Government, Darwin, NT, Australia
| | - Elizabeth E Roughead
- Quality Use of Medicine and Pharmacy Research Centre, UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Michael Ward
- Quality Use of Medicine and Pharmacy Research Centre, UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Stephanie E Reuter
- Quality Use of Medicine and Pharmacy Research Centre, UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Gregory Roberts
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Andre Q Andrade
- Quality Use of Medicine and Pharmacy Research Centre, UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
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Schultz HB, Hosseini A, McLachlan AJ, Reuter SE. Population Pharmacokinetics of Oral-Based Administration of Cannabidiol in Healthy Adults: Implications for Drug Development. Cannabis Cannabinoid Res 2023; 8:877-886. [PMID: 35443784 DOI: 10.1089/can.2021.0202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background and Objectives: Cannabidiol (CBD) is increasingly being studied as a therapeutic option for a range of health conditions; however, the pharmacokinetics of CBD is not well understood. This study characterized CBD pharmacokinetics in healthy adults using a population pharmacokinetic approach, informing drug development of oral-based dose forms of CBD. Materials and Methods: CBD concentration-time data were obtained from a phase I, randomized, open-label, four-way crossover study (n=12) and modeled using Phoenix NLME. Monte Carlo simulations were conducted to estimate CBD exposure with chronic dosing as intended for clinical use (50 mg b.i.d.). Results: A three-compartment pharmacokinetic model with a chain of absorption transit compartments and first-order elimination most adequately described CBD pharmacokinetics. Substantial variability in population pharmacokinetic parameters was identified (up to 60%CV), which could not be accounted for by any covariates. Simulations indicated a 3.6-fold difference in drug exposure at steady state with multiple dosing (AUCτ 95% prediction interval: 65.5-138 ng·h/mL), and variability in the time to reach steady state, which was predicted to be up to ∼3 weeks in some individuals (95% prediction interval: 18.6-297 h). Conclusions: The findings of this study have important implications for drug development. The lack of a clear dose-response relationship, due to large pharmacokinetic variability, indicates that a one-size-fits-all approach to CBD dosing may not be feasible, at least with current dosing approaches. Furthermore, an extended time to reach steady state means that the full effect of a selected dose level is not truly observed for some time and requires careful consideration in trial design.
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Affiliation(s)
- Hayley B Schultz
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Adele Hosseini
- Bod Australia Pty Ltd., Sydney, New South Wales, Australia
| | - Andrew J McLachlan
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, South Australia, Australia
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6
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Shafiei M, Galettis P, Beale P, Reuter SE, Martin JH, McLachlan AJ, Blinman P. Influence of age on pharmacokinetics of capecitabine and its metabolites in older adults with cancer: a pilot study. Cancer Chemother Pharmacol 2023:10.1007/s00280-023-04552-5. [PMID: 37351624 DOI: 10.1007/s00280-023-04552-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 06/09/2023] [Indexed: 06/24/2023]
Abstract
BACKGROUND Capecitabine is an oral chemotherapy prodrug of 5-fluorouracil (5-FU) with unpredictable toxicity, especially in older adults. The aim of this study was to evaluate the pharmacokinetics (PK) of capecitabine and its metabolites in younger adults (< 70 years) and older adults (≥ 70 years) receiving capecitabine for solid cancer. METHODS Eligible participants receiving capecitabine had 2 venous samples collected on day 14 of cycle 1 and cycle 2 of their treatment. Capecitabine and metabolite concentrations were determined using liquid chromatography with tandem mass spectrometry. A Bayesian estimation approach was used to generate individual estimates of PK parameters for 5-FU. A linear mixed-effect analysis of variance (ANOVA) model was used to compare dose-normalised log-transformed PK parameters between age groups. Correlations were determined by linear regression and logistic regression analyses. RESULTS Of the total 26 participants, 58% were male with a median age of 67 years (range, 37-85) with 54% aged < 70 years and 46% aged ≥ 70 years. Participants aged ≥ 70 years, compared to those aged < 70 years, had a greater 5-FU exposure based on area under the concentration-time curve (AUC) of 17% (90% CI 103-134%; 0.893 vs. 0.762 mg h/L) and 14% increase in maximal concentration, Cmax (90% CI 82.1-159%; 0.343 vs. 0.300 mg/L). The 5-FU Cmax was positively associated with time up and go (TUG) (Pearson's correlation 0.77, p = 0.01), but not other geriatric assessment domains or severe toxicity. CONCLUSION 5-FU exposure was significantly increased in older adults compared to younger adults receiving equivalent doses of capecitabine, and is a possible cause for increased toxicity in older adults.
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Affiliation(s)
- Mohsen Shafiei
- Concord Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.
- Concord Cancer Centre, Concord Repatriation General Hospital, Hospital Road, Concord, NSW, 2139, Australia.
| | - Peter Galettis
- Hunter Medical Research Institute, Kookaburra Circuit, New Lambton Heights, NSW, Australia
| | - Philip Beale
- Concord Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Jennifer H Martin
- Hunter Medical Research Institute, Kookaburra Circuit, New Lambton Heights, NSW, Australia
| | | | - Prunella Blinman
- Concord Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
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7
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Nguyen TA, Kirubakaran R, Schultz HB, Wong S, Reuter SE, McMullan B, Bolisetty S, Campbell C, Horvath AR, Stocker SL. Analytical and Non-Analytical Variation May Lead to Inappropriate Antimicrobial Dosing in Neonates: An In Silico Study. Clin Chem 2023:7146664. [PMID: 37116191 DOI: 10.1093/clinchem/hvad036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/01/2023] [Indexed: 04/30/2023]
Abstract
BACKGROUND Therapeutic drug monitoring (TDM) of aminoglycosides and vancomycin is used to prevent oto- and nephrotoxicity in neonates. Analytical and nonanalytical factors potentially influence dosing recommendations. This study aimed to determine the impact of analytical variation (imprecision and bias) and nonanalytical factors (accuracy of drug administration time, use of non-trough concentrations, biological variation, and dosing errors) on neonatal antimicrobial dosing recommendations. METHODS Published population pharmacokinetic models and the Australasian Neonatal Medicines Formulary were used to simulate antimicrobial concentration-time profiles in a virtual neonate population. Laboratory quality assurance data were used to quantify analytical variation in antimicrobial measurement methods used in clinical practice. Guideline-informed dosing recommendations based on drug concentrations were applied to compare the impact of analytical variation and nonanalytical factors on antimicrobial dosing. RESULTS Analytical variation caused differences in subsequent guideline-informed dosing recommendations in 9.3-12.1% (amikacin), 16.2-19.0% (tobramycin), 12.2-45.8% (gentamicin), and 9.6-19.5% (vancomycin) of neonates. For vancomycin, inaccuracies in drug administration time (45.6%), use of non-trough concentrations (44.7%), within-subject biological variation (38.2%), and dosing errors (27.5%) were predicted to result in more dosing discrepancies than analytical variation (12.5%). Using current analytical performance specifications, tolerated dosing discrepancies would be up to 14.8% (aminoglycosides) and 23.7% (vancomycin). CONCLUSIONS Although analytical variation can influence neonatal antimicrobial dosing recommendations, nonanalytical factors are more influential. These result in substantial variation in subsequent dosing of antimicrobials, risking inadvertent under- or overexposure. Harmonization of measurement methods and improved patient management systems may reduce the impact of analytical and nonanalytical factors on neonatal antimicrobial dosing.
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Affiliation(s)
- Thi A Nguyen
- School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Ranita Kirubakaran
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW, Australia
- Department of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Sydney, NSW, Australia
- Seberang Jaya Hospital, Penang, Malaysia
| | - Hayley B Schultz
- UniSA: Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Sherilyn Wong
- UniSA: Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Stephanie E Reuter
- UniSA: Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Brendan McMullan
- Department of Immunology and Infectious Diseases, Sydney Children's Hospital, Randwick, NSW, Australia
- Faculty of Medicine and Health, University of New South Wales, Sydney, NSW, Australia
| | - Srinivas Bolisetty
- Faculty of Medicine and Health, University of New South Wales, Sydney, NSW, Australia
| | - Craig Campbell
- NSW Health Pathology, Department of Chemical Pathology, Prince of Wales Hospital, Sydney, NSW, Australia
| | - Andrea R Horvath
- Faculty of Medicine and Health, University of New South Wales, Sydney, NSW, Australia
- NSW Health Pathology, Department of Chemical Pathology, Prince of Wales Hospital, Sydney, NSW, Australia
| | - Sophie L Stocker
- School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW, Australia
- Department of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Sydney, NSW, Australia
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Seah V, Sreeharan T, Kocic D, Reuter SE, Girgis L, Marriott DJE, Stocker SL. Effect of Therapeutic Plasma Exchange on Itraconazole Pharmacokinetics: A Case Study. Ther Drug Monit 2023; 45:129-132. [PMID: 36730858 DOI: 10.1097/ftd.0000000000001057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 10/08/2022] [Indexed: 02/04/2023]
Abstract
ABSTRACT The authors present the case of a 34-year-old male patient who underwent therapeutic plasma exchange (TPE) for amyopathic dermatomyositis. Immunosuppression resulted in Aspergillus lentulus pulmonary infection , requiring treatment with super bioavailable-itraconazole. Therapeutic itraconazole concentrations were attained after 2 weeks of treatment after dose adjustments. Interestingly, a substantial reduction in plasma itraconazole concentration was observed during TPE, which was attributed to an insufficient delay between the dosing of itraconazole and TPE initiation. Furthermore, there was an increase in plasma concentration post-TPE, which presumably reflects the redistribution of itraconazole from peripheral compartments back into plasma. This was confirmed by sampling of the TPE plasmapheresate, which revealed that changes in plasma concentration overestimated itraconazole clearance. These findings highlight that the pharmacokinetics of itraconazole are altered during TPE, which should be considered when timing drug administration and obtaining plasma concentrations.
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Affiliation(s)
- Vincent Seah
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital, Sydney
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney
| | - Thulashigan Sreeharan
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney
- Sydney School of Pharmacy, The University of Sydney, Sydney
| | - Danijela Kocic
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney
- Department of Chemical Pathology and Clinical Pharmacology, SydPath, St Vincent's Hospital, Sydney
| | - Stephanie E Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide; and
| | - Laila Girgis
- Department of Rheumatology, St Vincent's Hospital, Sydney, Australia
| | - Deborah J E Marriott
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital, Sydney
| | - Sophie L Stocker
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney
- Sydney School of Pharmacy, The University of Sydney, Sydney
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Lau C, Marriott D, Bui J, Figtree M, Gould M, Chubaty A, Su Y, Adhikari S, Konecny P, Kozierowski K, Holland T, Milliken E, Akram A, McNamara A, Sun Y, Hal SVAN, Patanwala AE, Shahabi-Sirjani A, Gray T, Yeo CY, Netluch A, Halena S, Appay M, Alameddine R, Yin F, Nguyen Q, So MY, Sandaradura I, Kim HY, Galimam S, Cerruto N, Lai T, Gilbey T, Daveson K, Reuter SE, Penm J, Alffenaar JW. LInezolid Monitoring to MInimise Toxicity (LIMMIT1): a multicentre retrospective review of patients receiving linezolid therapy and the impact of therapeutic drug monitoring. Int J Antimicrob Agents 2023; 61:106783. [PMID: 36921808 DOI: 10.1016/j.ijantimicag.2023.106783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/18/2023] [Accepted: 03/07/2023] [Indexed: 03/16/2023]
Abstract
BACKGROUND Linezolid is a broad-spectrum antimicrobial but toxicity limits it use. This study aimed to evaluate linezolid toxicity in a large multicentre cohort. Secondary objectives were to identify factors contributing to toxicity, including the impact of therapeutic drug monitoring (TDM). METHODS Patients administered linezolid between January 2017 and December 2019 were reviewed retrospectively. Data was collected on patient characteristics, linezolid therapy and outcomes. Descriptive statistics were performed on all patients, and statistical comparisons were undertaken between patients who did and did not experience linezolid toxicity. A multivariable logistic regression model was constructed to identify any covariates correlated with toxicity. RESULTS Linezolid was administered to 1,050 patients. Of these, 381 patients did not meet the inclusion criteria, and 47 patients were excluded as therapy ceased for non-toxicity reasons. There were 105/622 (16.9%) patients assessed to have linezolid toxicity. Those who experienced toxicity displayed a higher baseline creatinine (96.5µmol/L vs 79µmol/L, p=0.025), lower baseline platelet count (225 × 109/L vs 278.5 × 109/L, p=0.002), and received a longer course (median 21 vs 14 days, p<0.001) than patients who did not. Linezolid TDM was performed in 144 patients (23%). The multivariable logistic regression demonstrated that TDM-guided appropriate dose adjustment significantly reduced the odds of linezolid toxicity (aOR=0.45, 95%CI 0.21-0.96, p=0.038), and that treatment duration > 28 days was no longer significantly associated with toxicity. CONCLUSIONS This study confirmed linezolid treatment-limiting toxicity remains a problem, and suggests that TDM-guided dose optimisation may reduce the risk of toxicity and facilitate prolonged courses beyond 28 days.
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Affiliation(s)
- Cindy Lau
- Department of Pharmacy, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia; School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.
| | - Deborah Marriott
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia; School of Medicine, University of New South Wales, NSW, Australia
| | - Jessica Bui
- Department of Pharmacy, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Melanie Figtree
- Department of Clinical Microbiology and Infectious Diseases, Royal North Shore Hospital, St Leonards, NSW, Australia; School of Medicine, University of Sydney, NSW, Australia
| | - Michael Gould
- School of Medicine, University of Notre Dame Australia, NSW, Australia; Department of Intensive Care, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Adriana Chubaty
- Department of Pharmacy, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Yuen Su
- Department of Infectious Diseases, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Suman Adhikari
- Department of Pharmacy, St George Hospital, Kogarah, NSW, Australia; School of Clinical Medicine, The University of New South Wales, Sydney, Australia
| | - Pam Konecny
- School of Clinical Medicine, The University of New South Wales, Sydney, Australia; Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Kogarah, NSW, Australia
| | - Kristi Kozierowski
- Department of Pharmacy, John Hunter Hospital, New Lambton Heights, NSW, Australia
| | - Taylor Holland
- Department of Pharmacy, John Hunter Hospital, New Lambton Heights, NSW, Australia
| | - Eliza Milliken
- Department of Immunology and Infectious Diseases, John Hunter Hospital, New Lambton Heights, NSW, Australia
| | - Ayesha Akram
- Department of Immunology and Infectious Diseases, John Hunter Hospital, New Lambton Heights, NSW, Australia
| | - Alexander McNamara
- Department of Pharmacy, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Yihui Sun
- Department of Pharmacy, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Sebastiaan VAN Hal
- School of Medicine, University of Sydney, NSW, Australia; Department of Infectious Diseases and Microbiology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Asad E Patanwala
- Department of Pharmacy, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Aryan Shahabi-Sirjani
- Department of Pharmacy, Concord Repatriation General Hospital, Concord, NSW, Australia; Department of Microbiology and Infectious Diseases, Concord Repatriation General Hospital, Concord, NSW, Australia
| | - Timothy Gray
- School of Medicine, University of Sydney, NSW, Australia; Department of Microbiology and Infectious Diseases, Concord Repatriation General Hospital, Concord, NSW, Australia
| | - Chin Yen Yeo
- Department of Pharmacy, Blacktown Hospital, Blacktown, NSW, Australia
| | - Angela Netluch
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | - Stephanie Halena
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | - Marcelle Appay
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | | | - Fiona Yin
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | - Quoc Nguyen
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | - Mei-Yi So
- Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia
| | - Indy Sandaradura
- School of Medicine, University of Sydney, NSW, Australia; Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, NSW, Australia; Sydney Institute for Infectious Diseases, University of Sydney, Camperdown, NSW, Australia
| | - Hannah Yejin Kim
- School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia; Sydney Institute for Infectious Diseases, University of Sydney, Camperdown, NSW, Australia
| | - Semun Galimam
- Department of Pharmacy, Gosford and Wyong Hospitals, NSW, Australia
| | - Nicole Cerruto
- Department of Pharmacy, Gosford and Wyong Hospitals, NSW, Australia
| | - Tony Lai
- Sydney Institute for Infectious Diseases, University of Sydney, Camperdown, NSW, Australia; Department of Pharmacy, Children's Hospital Westmead, Westmead, NSW, Australia
| | - Timothy Gilbey
- Department of Infectious Diseases, Wagga Wagga Base Hospital, Wagga Wagga, NSW, Australia
| | - Kathryn Daveson
- Department of Infectious Diseases, The Canberra Hospital, Canberra, ACT, Australia
| | - Stephanie E Reuter
- UniSA Clinical and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Jonathan Penm
- School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Department of Pharmacy, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Jan-Willem Alffenaar
- School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Department of Pharmacy, Westmead Hospital, Westmead, NSW, Australia; Sydney Institute for Infectious Diseases, University of Sydney, Camperdown, NSW, Australia
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10
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Carland JE, Stacy AE, Schaffer AL, Day RO, Brett J, Reuter SE, Stocker SL. Blood, dose recommendation reports and phone calls: Experiences of a therapeutic drug monitoring advisory service for vancomycin. Br J Clin Pharmacol 2023; 89:1896-1902. [PMID: 36662777 DOI: 10.1111/bcp.15668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/18/2022] [Accepted: 01/14/2023] [Indexed: 01/21/2023] Open
Abstract
Dose-prediction software is recommended to enable area under the curve over 24 h (AUC24 )-guided dosing of the antibiotic vancomycin. However, uncertainty remains about how best to implement software in the clinic. We describe the activity, over 18 months, of a consultative therapeutic drug monitoring Advisory Service (the Service) for vancomycin that used dose-prediction software alongside clinical expertise, identifying factors that influence attainment of therapeutic targets. Of the 408 vancomycin dose reports provided for 182 courses of therapy, most (57%) recommended a dose change. The majority (82.8%, 193/233) of recommended dose adjustments were accepted by treating teams. A dose report was not published for 125 courses of therapy, with reasons including patient in intensive care unit or service error. An estimated 26.6 h of staff time was allocated to Service activities each month. Publication of a dose report facilitated attainment of therapeutic targets (P = .002). Software integration could improve Service outcomes, avoiding errors and reducing staff workload.
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Affiliation(s)
- Jane E Carland
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW, Sydney, Australia
| | - Alexandra E Stacy
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,The School of Medicine, The University of Notre Dame Australia, Sydney, Australia
| | - Andrea L Schaffer
- Centre for Big Data Research in Health, Faculty of Medicine, UNSW, Sydney, Australia
| | - Richard O Day
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW, Sydney, Australia
| | - Jonathan Brett
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW, Sydney, Australia.,Centre for Big Data Research in Health, Faculty of Medicine, UNSW, Sydney, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, Australia
| | - Sophie L Stocker
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,School of Clinical Medicine, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, UNSW, Sydney, Australia.,School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
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11
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Abstract
INTRODUCTION Vancomycin dosing decisions are informed by factors such as body weight and renal function. It is important to understand the impact of obesity on vancomycin pharmacokinetics and how this may influence dosing decisions. Vancomycin dosing guidelines use varied descriptors of body weight and renal function. There is uncertainty whether current dosing guidelines result in attainment of therapeutic targets in obese individuals. AREAS COVERED Literature was explored using PubMed, Embase and Google Scholar for articles from January 1980 to July 2021 regarding obesity-driven physiological changes, their influence on vancomycin pharmacokinetics and body size descriptors and renal function calculations in vancomycin dosing. Pharmacokinetic simulations reflective of international vancomycin dosing guidelines were conducted to evaluate the ability of using total, ideal and adjusted body weight, as well as Cockcroft-Gault and CKD-EPI equations to attain an area-under-the-curve to minimum inhibitory concentration ratio (AUC24/MIC) target (400-650) in obese individuals. EXPERT OPINION Vancomycin pharmacokinetics in obese individuals remains debated. Guidelines that determine loading doses using total body weight, and maintenance doses adjusted based on renal function and adjusted body weight, may be most appropriate for obese individuals. Use of ideal body weight leads to subtherapeutic vancomycin exposure and underestimation of renal function.
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Affiliation(s)
- Sherilyn Wong
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, Australia
| | - Stephanie E Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, Australia
| | - Graham Rd Jones
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia.,Department of Chemical Pathology and Clinical Pharmacology, SydPath, St Vincent's Hospital, Darlinghurst, Australia
| | - Sophie L Stocker
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia.,Sydney School of Pharmacy, The University of Sydney, Sydney, Australia.,Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital Sydney, Darlinghurst, Australia
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12
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Wong DD, van Zuylen WJ, Novos T, Stocker S, Reuter SE, Au J, Foster CSP, Day RO, Horvath AR, Endre Z, Rawlinson WD. Detection of Ganciclovir-Resistant Cytomegalovirus in a Prospective Cohort of Kidney Transplant Recipients Receiving Subtherapeutic Valganciclovir Prophylaxis. Microbiol Spectr 2022; 10:e0268421. [PMID: 35658598 PMCID: PMC9241781 DOI: 10.1128/spectrum.02684-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/20/2022] [Indexed: 11/20/2022] Open
Abstract
Cytomegalovirus infection during antiviral prophylaxis occurs in transplant recipients despite individualized regimens based on renal function. Fifty kidney transplant recipients were assessed between 2016 and 2019 for valganciclovir dosing, ganciclovir exposure, cytomegalovirus infection, and genotypic resistance markers during the first year posttransplant. Ganciclovir plasma concentrations were measured using mass spectrometry. Population pharmacokinetics was used to determine individual ganciclovir exposure and to evaluate the ability of manufacturer dosing guidelines to meet therapeutic target daily area under the curve (AUC24) of 40 to 50 μg·h/mL. Full-length UL54 and UL97 were assessed using high-throughput sequencing in cytomegalovirus DNA-positive patient specimens. Valganciclovir doses administered to recipients with creatinine clearance of <40 mL/min were higher than specified by guidelines, and they were lower for recipients with creatinine clearance of ≥40 mL/min. The mean ganciclovir AUC24 was 33 ± 13 μg·h/mL, and 82% of subjects did not attain the therapeutic target. Pharmacokinetic simulations showed that the guidelines similarly could not attain the therapeutic target in 79% of individuals. Cytomegalovirus breakthrough occurred in 6% (3/50) of recipients, while 12% (6/50) developed late-onset infection. The mean AUC24s of recipients with (n = 3) and without (n = 47) infection were not significantly different (P = 0.528). However, one recipient with an AUC24 of 20 μg·h/mL acquired two UL97 ganciclovir resistance mutations. Current prophylaxis guidelines resulted in subtherapeutic ganciclovir exposure in several study recipients, including the emergence of resistance genotypes. IMPORTANCE This study examined the pharmacokinetics and viral genomic data from a prospective cohort of kidney transplant recipients undergoing valganciclovir prophylaxis for cytomegalovirus (CMV) prevention. We showed for the first time using high-throughput sequencing the detection of ganciclovir resistance mutations in breakthrough CMV infection during subtherapeutic plasma ganciclovir as indicated by the pharmacokinetic parameter daily area under the curve (AUC24). In addition, we found that current valganciclovir dosing guidelines for CMV prophylaxis are predicted to attain therapeutic targets in only 21% of recipients, which is consistent with previous pharmacokinetic studies. The novel findings of resistance mutations during subtherapeutic ganciclovir exposure presented here can inform future studies investigating the dynamics of drug selection pressure and the emergence of resistance mutations in vivo.
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Affiliation(s)
- Diana D. Wong
- Serology and Virology Division, NSW Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Wendy J. van Zuylen
- Serology and Virology Division, NSW Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Talia Novos
- Department of Chemical Pathology, New South Wales Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - Sophie Stocker
- Sydney Pharmacy School, Faculty of Medicine & Health, The University of Sydney, Sydney, New South Wales, Australia
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Sydney, New South Wales, Australia
- St Vincent’s Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Stephanie E. Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Jane Au
- Serology and Virology Division, NSW Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - Charles S. P. Foster
- Serology and Virology Division, NSW Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Richard O. Day
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Sydney, New South Wales, Australia
- St Vincent’s Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Andrea R. Horvath
- Department of Chemical Pathology, New South Wales Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - Zoltan Endre
- Department of Nephrology, Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - William D. Rawlinson
- Serology and Virology Division, NSW Health Pathology, Prince of Wales Hospital, Sydney, New South Wales, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, Sydney, New South Wales, Australia
- School of Biotechnology and Biomolecular Sciences, University of New South Wales Sydney, Sydney, New South Wales, Australia
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13
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Reuter SE, Stocker SL, Alffenaar JWC, Baldelli S, Cattaneo D, Jones G, Koch BCP, Kocic D, Mathew SK, Molinaro M, Neely M, Sandaradura I, Marriott DJE. Optimal Practice for Vancomycin Therapeutic Drug Monitoring: Position Statement From the Anti-infectives Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology. Ther Drug Monit 2022; 44:121-132. [PMID: 34882107 DOI: 10.1097/ftd.0000000000000944] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/08/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Individualization of vancomycin dosing based on therapeutic drug monitoring (TDM) data is known to improve patient outcomes compared with fixed or empirical dosing strategies. There is increasing evidence to support area-under-the-curve (AUC24)-guided TDM to inform vancomycin dosing decisions for patients receiving therapy for more than 48 hours. It is acknowledged that there may be institutional barriers to the implementation of AUC24-guided dosing, and additional effort is required to enable the transition from trough-based to AUC24-based strategies. Adequate documentation of sampling, correct storage and transport, accurate laboratory analysis, and pertinent data reporting are required to ensure appropriate interpretation of TDM data to guide vancomycin dosing recommendations. Ultimately, TDM data in the clinical context of the patient and their response to treatment should guide vancomycin therapy. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology, the IATDMCT Anti-Infectives Committee, provides recommendations with respect to best clinical practice for vancomycin TDM.
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Affiliation(s)
- Stephanie E Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, Australia
| | - Sophie L Stocker
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, Australia
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Jan-Willem C Alffenaar
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Department of Pharmacy, Westmead Hospital, Sydney, Australia
- Marie Bashir Institute of Infectious Diseases and Biosecurity, The University of Sydney, Sydney, Australia
| | - Sara Baldelli
- Unit of Clinical Pharmacology, ASST Fatebenefratelli Sacco University Hospital, Milan, Italy
| | - Dario Cattaneo
- Unit of Clinical Pharmacology, ASST Fatebenefratelli Sacco University Hospital, Milan, Italy
| | - Graham Jones
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
- Department of Chemical Pathology and Clinical Pharmacology, SydPath, St Vincent's Hospital, Sydney, Australia
| | - Birgit C P Koch
- Department of Hospital Pharmacy, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Danijela Kocic
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
- Department of Chemical Pathology and Clinical Pharmacology, SydPath, St Vincent's Hospital, Sydney, Australia
| | - Sumith K Mathew
- Department of Pharmacology and Clinical Pharmacology, Christian Medical College, Vellore, India
| | - Mariadelfina Molinaro
- Department of Diagnostic Medicine, Clinical and Experimental Pharmacokinetics Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Michael Neely
- Department of Pediatrics, Keck School of Medicine, University of Southern California, and Division of Infectious Diseases, Children's Hospital Los Angeles, Los Angeles, California, Los Angeles, CA
| | - Indy Sandaradura
- Marie Bashir Institute of Infectious Diseases and Biosecurity, The University of Sydney, Sydney, Australia
- Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Centre for Infectious Diseases and Microbiology, Westmead Hospital, Sydney, Australia
- Institute for Clinical Pathology and Medical Research, NSW Health Pathology, Sydney, Australia; and
| | - Deborah J E Marriott
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital, Sydney, Australia
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14
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Lau C, Marriott D, Schultz HB, Gould M, Andresen D, Wicha SG, Alffenaar JW, Penm J, Reuter SE. Assessment of cefepime toxicodynamics: comprehensive examination of pharmacokinetic/pharmacodynamic targets for cefepime-induced neurotoxicity and evaluation of current dosing guidelines. Int J Antimicrob Agents 2021; 58:106443. [PMID: 34551358 DOI: 10.1016/j.ijantimicag.2021.106443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/19/2021] [Accepted: 09/12/2021] [Indexed: 01/24/2023]
Abstract
BACKGROUND Cefepime-induced neurotoxicity (CIN) is an increasingly reported adverse event; however, the toxicity threshold remains unclear. This study was conducted to provide a comprehensive examination of the most appropriate threshold for CIN, and evaluate the ability of current dosing regimens to attain therapeutic targets. METHODS Data of the incidence of CIN and cefepime plasma concentrations were collected retrospectively from patients administered cefepime. Population pharmacokinetic modelling was used to determine daily cefepime trough concentration (Cmin), maximum serum concentration and area under the concentration-time curve. The ability of each pharmacokinetic parameter to predict CIN was evaluated using receiver operating characteristic (ROC) curves, from which optimal toxicity thresholds were determined. Pharmacokinetic simulation was used to evaluate the ability of cefepime dosing guidelines to meet established efficacy targets, whilst maintaining exposure below the determined CIN threshold. RESULTS In total, 102 cefepime courses were evaluated, with CIN reported in 10. ROC analyses showed that all cefepime pharmacokinetic parameters were strongly predictive of CIN. Cmin of 49 mg/L was identified as the optimal toxicity target, based on its predictive ability (0.88, 95% confidence interval 0.758-0.999, P<0.001) and ease of clinical use. Assessment of cefepime dosing regimens predicted that only 29% of simulated patients achieve therapeutic targets, with patients with impaired renal function more likely to exhibit subtherapeutic concentrations (89%), and patients with normal renal function likely to have potentially toxic exposure (64%). CONCLUSIONS The findings from this study provide evidence that cefepime exposure is highly predictive of CIN, with Cmin of 49 mg/L being the most appropriate toxicity threshold. Further research is required to optimize cefepime dosing in the context of this therapeutic target.
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Affiliation(s)
- Cindy Lau
- Department of Pharmacy, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia; The University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney, NSW, Australia.
| | - Deborah Marriott
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia; School of Medicine, University of New South Wales, NSW, Australia
| | - Hayley B Schultz
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Michael Gould
- School of Medicine, University of Notre Dame Australia, NSW, Australia; Department of Intensive Care, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - David Andresen
- Department of Clinical Microbiology and Infectious Diseases, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia; School of Medicine, University of Notre Dame Australia, NSW, Australia
| | - Sebastian G Wicha
- Department of Clinical Pharmacy, Institute of Pharmacy, University of Hamburg, Hamburg, Germany
| | - Jan-Willem Alffenaar
- The University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney, NSW, Australia; Westmead Hospital, Westmead, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney, NSW, Australia
| | - Jonathan Penm
- The University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney, NSW, Australia; Department of Pharmacy, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
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15
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Lau C, Marriott D, Gould M, Andresen D, Reuter SE, Penm J. A retrospective study to determine the cefepime-induced neurotoxicity threshold in hospitalized patients. J Antimicrob Chemother 2021; 75:718-725. [PMID: 31711216 DOI: 10.1093/jac/dkz476] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES Cefepime-induced neurotoxicity (CIN) has been demonstrated to be associated with cefepime plasma concentrations; however, the toxicity threshold remains unclear. The primary objective of this study was to identify the cefepime plasma trough concentration at which neurotoxicity occurs. Secondary objectives were to determine the incidence of CIN at a large tertiary institution and to identify patient factors associated with the development of CIN. METHODS A retrospective review of all adult patients administered cefepime between October 2017 and May 2018 in a tertiary hospital was conducted to determine total incidence of CIN. A receiver operating characteristic (ROC) curve was constructed to review the sensitivity and specificity of using various cefepime trough plasma concentrations to predict the development of neurotoxicity. Cefepime plasma concentrations were measured using ultra-HPLC. A regression was conducted to identify patient factors associated with CIN. RESULTS In total, 206 patients were administered 259 courses of cefepime, with an overall CIN incidence of 6% (16/259 courses). A total of 64 courses had a cefepime trough concentration measured (24.7%). A cefepime trough concentration of 36 mg/L provided the best differentiation between patients who experienced neurotoxicity and those who did not. No other patient covariates were identified to be significantly associated with neurotoxicity occurring. CONCLUSIONS A cefepime trough plasma concentration ≥36 mg/L appears to be the most sensitive and specific cut-off to predict CIN occurring. No patient factors were associated with the development of CIN when accounting for cefepime trough plasma concentrations.
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Affiliation(s)
- Cindy Lau
- Department of Pharmacy, St Vincent's Hospital, Sydney, NSW, Australia.,The University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney, NSW, Australia
| | - Deborah Marriott
- Department of Infectious Diseases and Clinical Microbiology, St Vincent's Hospital, Sydney, NSW, Australia.,School of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Michael Gould
- School of Medicine, University of Notre Dame Australia, Sydney, NSW, Australia
| | - David Andresen
- Department of Infectious Diseases and Clinical Microbiology, St Vincent's Hospital, Sydney, NSW, Australia.,School of Medicine, University of Notre Dame Australia, Sydney, NSW, Australia
| | - Stephanie E Reuter
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Jonathan Penm
- The University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney, NSW, Australia
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16
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Reuter SE, Schultz HB, Ward MB, Grant CL, Paech GM, Banks S, Evans AM. The effect of high-dose, short-term caffeine intake on the renal clearance of calcium, sodium and creatinine in healthy adults. Br J Clin Pharmacol 2021; 87:4461-4466. [PMID: 33852164 DOI: 10.1111/bcp.14856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 03/14/2021] [Indexed: 11/30/2022] Open
Abstract
The consumption of caffeine has been linked to osteoporosis, believed to be due to enhanced bone resorption as a result of increased calcium excretion in the urine. However, the amount of calcium in the urine may not necessarily reflect the true effect of caffeine on calcium clearance. This study therefore examined the impact of high-dose, short-term caffeine intake on renal clearance of calcium, sodium and creatinine in healthy adults. In a double-blind clinical study, participants chewed caffeine (n = 12) or placebo (n = 12) gum for 5 minutes at 2-hour intervals over a 6-hour treatment period (800 mg total caffeine). Caffeine increased renal calcium clearance by 77%. Furthermore, the effect was positively correlated with sodium clearance and urine volume, suggesting that caffeine may act through inhibition of sodium reabsorption in the proximal convoluted tubule. This study confirmed that caffeine does increase renal calcium clearance and fosters further investigation into safe consumption of caffeine.
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Affiliation(s)
- Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Hayley B Schultz
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Michael B Ward
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Crystal L Grant
- Behaviour-Brain-Body Research Group, UniSA Justice & Society, University of South Australia, Adelaide, SA, Australia
| | - Gemma M Paech
- Behaviour-Brain-Body Research Group, UniSA Justice & Society, University of South Australia, Adelaide, SA, Australia.,Department of Respiratory & Sleep Medicine, John Hunter Hospital, Newcastle, NSW, Australia
| | - Siobhan Banks
- Behaviour-Brain-Body Research Group, UniSA Justice & Society, University of South Australia, Adelaide, SA, Australia
| | - Allan M Evans
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
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17
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Roydhouse SA, Carland JE, Debono DS, Baysari MT, Reuter SE, Staciwa AJ, Sandhu APK, Day RO, Stocker SL. Accuracy of documented administration times for intravenous antimicrobial drugs and impact on dosing decisions. Br J Clin Pharmacol 2021; 87:4273-4282. [PMID: 33792079 DOI: 10.1111/bcp.14844] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 03/03/2021] [Accepted: 03/08/2021] [Indexed: 11/27/2022] Open
Abstract
AIMS Accurate documentation of medication administration time is imperative for many therapeutic decisions, including dosing of intravenous antimicrobials. The objectives were to determine (1) the discrepancy between actual and documented administration times for antimicrobial infusions and (2) whether day of the week, time of day, nurse-to-patient ratio and drug impacted accuracy of documented administration times. METHODS Patient and dosing data were collected (June-August 2019) for 55 in-patients receiving antimicrobial infusions. "Documented" and "actual" administration times (n = 660) extracted from electronic medication management systems and smart infusion pumps, respectively, were compared. Influence of the day (weekday/weekend), time of day (day/evening/night), nurse-to-patient ratio (high 1:1/low 1:5) and drug were examined. Monte Carlo simulation was used to predict the impact on dose adjustments for vancomycin using the observed administration time discrepancies compared to the actual administration time. RESULTS The median discrepancy between actual and documented administration times was 16 min (range, 2-293 min), with discrepancies greater than 60 minutes in 7.7% of administrations. Overall, discrepancies (median [range]) were similar on weekends (17 [2-293] min) and weekdays (16 [2-188] min), and for high (16 [2-157] min) and low nurse-to-patient ratio wards (16 [2-293] min). Discrepancies were smallest for night administrations (P < .05), and antimicrobials with shorter half-lives (P < .0001). The observed discrepancies in vancomycin administration time resulted in a different dose recommendation in 58% of cases (30% higher, 28% lower). CONCLUSIONS Overall, there were discrepancies between actual and documented antimicrobial infusion administration times. For vancomycin, these discrepancies in administration time were predicted to result in inappropriate dose recommendations.
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Affiliation(s)
- Stephanie A Roydhouse
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, Sydney, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Jane E Carland
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, Sydney, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Deborah S Debono
- Centre for Health Services Management, School of Public Health, The University of Technology Sydney, Sydney, Australia
| | - Melissa T Baysari
- Sydney School of Health Sciences, Charles Perkins Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Stephanie E Reuter
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, Australia
| | - Alice J Staciwa
- Pharmacy Department, St Vincent's Hospital Sydney, Sydney, Australia
| | - Anmol P K Sandhu
- Pharmacy Department, St Vincent's Hospital Sydney, Sydney, Australia
| | - Richard O Day
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, Sydney, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Sophie L Stocker
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital Sydney, Sydney, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia.,Sydney Pharmacy School, The University of Sydney, Sydney, Australia
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18
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Sandaradura I, Marriott DJE, Day RO, Norris RLG, Pang E, Stocker SL, Reuter SE. Current fluconazole treatment regimens result in under-dosing of critically ill adults during early therapy. Eur J Clin Microbiol Infect Dis 2021; 40:1521-1528. [PMID: 33638727 DOI: 10.1007/s10096-021-04201-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/16/2021] [Indexed: 01/30/2023]
Abstract
PURPOSE To evaluate current fluconazole treatment regimens in critically ill adults over the typical treatment course. METHODS Data from critically ill adults treated with fluconazole (n=30) were used to develop a population pharmacokinetic model. Probability of target attainment (PTA) (fAUC24/MIC >100) was determined from simulations for four previously proposed treatment regimens: (i) 400 mg once daily, (ii) an 800 mg loading dose followed by 400 mg once daily, (iii) 400 mg twice daily, and (iv) a 12 mg/kg loading dose followed by 6 mg/kg once daily. The effect of body weight (40, 70, 120 kg) and renal function (continuous renal replacement therapy (CRRT); 20, 60, 120, 180 mL/min creatinine clearance) on PTA was assessed. RESULTS Early (0-48 h) fluconazole target attainment for infections with a minimum inhibitory concentration (MIC) of 2 mg/L was highly variable. PTA was highest with an 800 mg loading dose for underweight (40 kg) patients and with a 12 mg/kg loading dose for the remainder. End-of-treatment PTA was highest with the 400 mg twice daily maintenance dosing for patients who were under- or normal weight and 6 mg/kg maintenance dosing for overweight (120 kg) patients. None of the fluconazole regimens reliably attained early targets for MICs of ≥4 mg/L. CONCLUSION Current fluconazole dosing regimens do not achieve adequate early target attainment in critically ill adults, particularly in those who are overweight, have higher creatinine clearance, or are undergoing CRRT. Current fluconazole dosing strategies are generally inadequate to treat organisms with an MIC of ≥4 mg/L.
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Affiliation(s)
- Indy Sandaradura
- Centre for Infectious Diseases and Microbiology, Westmead Hospital, Sydney, NSW, Australia.
- Department of Microbiology, St Vincent's Hospital, Sydney, NSW, Australia.
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia.
- Faculty of Medicine and Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
| | - Deborah J E Marriott
- Department of Microbiology, St Vincent's Hospital, Sydney, NSW, Australia
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Richard O Day
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
| | - Ross L G Norris
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
- Discipline of Clinical Pharmacology, School of Medicine & Public Health, University of Newcastle, Newcastle, NSW, Australia
- Hunter Medical Research Institute, Kookaburra Circuit, New Lambton Heights, NSW, Australia
| | - Edna Pang
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
| | - Sophie L Stocker
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
- Faculty of Medicine and Health, Sydney Pharmacy School, University of Sydney, Sydney, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
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19
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Sandaradura I, Wojciechowski J, Marriott DJE, Day RO, Stocker S, Reuter SE. Model-Optimized Fluconazole Dose Selection for Critically Ill Patients Improves Early Pharmacodynamic Target Attainment without the Need for Therapeutic Drug Monitoring. Antimicrob Agents Chemother 2021; 65:e02019-20. [PMID: 33361309 PMCID: PMC8092533 DOI: 10.1128/aac.02019-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/20/2020] [Indexed: 12/19/2022] Open
Abstract
Fluconazole has been associated with higher mortality compared with the echinocandins in patients treated for invasive candida infections. Underexposure from current fluconazole dosing regimens may contribute to these worse outcomes, so alternative dosing strategies require study. The objective of this study was to evaluate fluconazole drug exposure in critically ill patients comparing a novel model-optimized dose selection method with established approaches over a standard 14-day (336-h) treatment course. Target attainment was evaluated in a representative population of 1,000 critically ill adult patients for (i) guideline dosing (800-mg loading and 400-mg maintenance dosing adjusted to renal function), (ii) guideline dosing followed by therapeutic drug monitoring (TDM)-guided dose adjustment, and (iii) model-optimized dose selection based on patient factors (without TDM). Assuming a MIC of 2 mg/liter, free fluconazole 24-h area under the curve (fAUC24) targets of ≥200 mg · h/liter and <800 mg · h/liter were used for assessment of target attainment. Guideline dosing resulted in underexposure in 21% of patients at 48 h and in 23% of patients at 336 h. The TDM-guided strategy did not influence 0- to 48-h target attainment due to inherent procedural delays but resulted in 37% of patients being underexposed at 336 h. Model-optimized dosing resulted in ≥98% of patients meeting efficacy targets throughout the treatment course, while resulting in less overexposure compared with guideline dosing (7% versus 14%) at 336 h. Model-optimized dose selection enables fluconazole dose individualization in critical illness from the outset of therapy and should enable reevaluation of the comparative effectiveness of this drug in patients with severe fungal infections.
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Affiliation(s)
- Indy Sandaradura
- Centre for Infectious Diseases and Microbiology, Westmead Hospital, Sydney, NSW, Australia
- Department of Microbiology, St Vincent's Hospital, Sydney, NSW, Australia
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
- School of Medicine, University of Sydney, NSW, Australia
| | | | - Deborah J E Marriott
- Department of Microbiology, St Vincent's Hospital, Sydney, NSW, Australia
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Richard O Day
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
- Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
| | - Sophie Stocker
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
- Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
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20
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Stocker SL, Carland JE, Reuter SE, Stacy AE, Schaffer AL, Stefani M, Lau C, Kirubakaran R, Yang JJ, Shen CFJ, Roberts DM, Marriott DJE, Day RO, Brett J. Evaluation of a Pilot Vancomycin Precision Dosing Advisory Service on Target Exposure Attainment Using an Interrupted Time Series Analysis. Clin Pharmacol Ther 2020; 109:212-221. [PMID: 33190285 DOI: 10.1002/cpt.2113] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/10/2020] [Indexed: 12/30/2022]
Abstract
This study evaluated the ability of a pilot therapeutic drug monitoring (TDM) Advisory Service to facilitate vancomycin therapeutic target attainment within a real-world clinical setting. The Service provided area under the concentration-time curve (AUC)-guided vancomycin dose recommendations, using Bayesian forecasting software and clinical expertise, to prescribers at an Australian hospital. A retrospective audit of intravenous vancomycin therapy (> 48 hours) in adults (≥ 18 years old) was undertaken over a 54-month period to evaluate attainment of established vancomycin pharmacokinetic/pharmacodynamic targets (AUC over 24 hours / minimum inhibitory concentration: 400-600) before (36-month period) and after (18-month period) Service implementation. Interrupted time series analysis was employed to evaluate monthly measures of the median proportion of therapy spent within the target range. Indices of time to target attainment were also assessed before and after Service implementation. The final cohort comprised 1,142 courses of vancomycin (816 patients); 835 courses (596 patients) and 307 courses (220 patients) administered before and after Service implementation, respectively. Prior to piloting the Service, the median proportion of time in the target range was 40.1% (95% CI, 34.3-46.0%); this increased by 10.4% (95% CI, 1.2-19.6%, P = 0.03) after the Service, and was sustained throughout the post-Service evaluation period. Post-Service target attainment at 48-72 hours after initiation of therapy was increased (7.8%, 95% CI, 1.3-14.3%, P = 0.02). The findings of this study provide evidence that a consultative TDM Service can facilitate attainment of vancomycin therapeutic targets; however, optimization of the Service may further improve the use of vancomycin.
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Affiliation(s)
- Sophie L Stocker
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia.,Sydney Pharmacy School, Faculty of Medicine & Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Jane E Carland
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Alexandra E Stacy
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,School of Medicine, The University of Notre Dame Australia, Sydney, New South Wales, Australia
| | - Andrea L Schaffer
- Centre for Big Data Research in Health, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Maurizio Stefani
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Cindy Lau
- Sydney Pharmacy School, Faculty of Medicine & Health, The University of Sydney, Sydney, New South Wales, Australia.,Pharmacy Department, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Ranita Kirubakaran
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Jennifer J Yang
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Catriona F J Shen
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Darren M Roberts
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Deborah J E Marriott
- St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia.,Department of Clinical Microbiology & Infectious Diseases, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Richard O Day
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
| | - Jonathan Brett
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, New South Wales, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, New South Wales, Australia
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21
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Teng C, Reuter SE, Blinman PL, Dhillon HM, Galettis P, Proschogo N, McLachlan AJ, Vardy JL. Ibudilast for prevention of oxaliplatin-induced acute neurotoxicity: a pilot study assessing preliminary efficacy, tolerability and pharmacokinetic interactions in patients with metastatic gastrointestinal cancer. Cancer Chemother Pharmacol 2020; 86:547-558. [PMID: 32949265 DOI: 10.1007/s00280-020-04143-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/06/2020] [Indexed: 01/07/2023]
Abstract
PURPOSE This prospective, open-label, sequential 'before vs. after' pilot study was conducted to provide preliminary efficacy and tolerability data for ibudilast in the prevention of oxaliplatin-induced neurotoxicity in patients with metastatic upper gastrointestinal or colorectal cancer. Any potential impact of ibudilast on oxaliplatin and 5-fluorouracil pharmacokinetics was also explored. METHODS Participants were administered a chemotherapy cycle (FOLFOX or CapeOx), followed by a chemotherapy cycle with co-administration of ibudilast 30 mg b.i.d. p.o. Efficacy was assessed on Day 3 and end of cycle using the Oxaliplatin-Specific Neurotoxicity Scale (OSNS) and additional clinical/patient-reported neurotoxicity measures. A population pharmacokinetic approach was used to determine oxaliplatin and 5-fluorouracil pharmacokinetics with and without ibudilast. RESULTS Sixteen participants consented; 14 completed both chemotherapy cycles. Across all measures, the majority of participants experienced either an improvement or no worsening of neurotoxicity with ibudilast treatment. Based on OSNS assessments, acute neurotoxicity was unchanged in 12/14 participants and improved in 2/14 participants. The 90% confidence interval (CI) of the dose-normalised ratio of oxaliplatin AUC (90% CI 95.0-109%) and 5-fluorouracil AUC (90% CI 66.5-173%) indicated no significant impact of ibudilast on systemic exposure. CONCLUSION This pilot study indicated ibudilast co-administration may improve or stabilise oxaliplatin-induced neurotoxicity. Given the expected worsening of symptoms in patients with continued chemotherapy, this represents a signal of effect that warrants further investigation. Pharmacokinetic analysis indicates ibudilast has no significant effect on oxaliplatin pharmacokinetics, and is unlikely to influence pharmacokinetics of 5-fluorouracil. CLINICAL TRIAL REGISTRATION Trial registration number: UTN U1111-1209-0075 and ANZCTRN12618000232235 (registered 13/02/2018).
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Affiliation(s)
- Christina Teng
- Department of Medical Oncology, Concord Cancer Centre, Concord Repatriation General Hospital, Concord, Australia
- Central Coast Cancer Centre, Gosford, Australia
- Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia
| | - Stephanie E Reuter
- Clinical and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Prunella L Blinman
- Department of Medical Oncology, Concord Cancer Centre, Concord Repatriation General Hospital, Concord, Australia
- Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia
| | - Haryana M Dhillon
- Centre for Medical Psychology and Evidence-Based Decision-Making, University of Sydney, Camperdown, Australia
| | - Peter Galettis
- School of Medicine and Public Health, University of Newcastle, Callaghan, Australia
| | | | | | - Janette L Vardy
- Department of Medical Oncology, Concord Cancer Centre, Concord Repatriation General Hospital, Concord, Australia.
- Centre for Medical Psychology and Evidence-Based Decision-Making, University of Sydney, Camperdown, Australia.
- Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia.
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22
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Shingde RV, Reuter SE, Graham GG, Carland JE, Williams KM, Day RO, Stocker SL. Assessing the accuracy of two Bayesian forecasting programs in estimating vancomycin drug exposure. J Antimicrob Chemother 2020; 75:3293-3302. [DOI: 10.1093/jac/dkaa320] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 06/28/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Current guidelines for intravenous vancomycin identify drug exposure (as indicated by the AUC) as the best pharmacokinetic (PK) indicator of therapeutic outcome.
Objectives
To assess the accuracy of two Bayesian forecasting programs in estimating vancomycin AUC0–∞ in adults with limited blood concentration sampling.
Methods
The application of seven vancomycin population PK models in two Bayesian forecasting programs was examined in non-obese adults (n = 22) with stable renal function. Patients were intensively sampled following a single (1000 mg or 15 mg/kg) dose. For each patient, AUC was calculated by fitting all vancomycin concentrations to a two-compartment model (defined as AUCTRUE). AUCTRUE was then compared with the Bayesian-estimated AUC0–∞ values using a single vancomycin concentration sampled at various times post-infusion.
Results
Optimal sampling times varied across different models. AUCTRUE was generally overestimated at earlier sampling times and underestimated at sampling times after 4 h post-infusion. The models by Goti et al. (Ther Drug Monit 2018;
40
212–21) and Thomson et al. (J Antimicrob Chemother 2009;
63
1050–7) had precise and unbiased sampling times (defined as mean imprecision <25% and <38 mg·h/L, with 95% CI for mean bias containing zero) between 1.5 and 6 h and between 0.75 and 2 h post-infusion, respectively. Precise but biased sampling times for Thomson et al. were between 4 and 6 h post-infusion.
Conclusions
When using a single vancomycin concentration for Bayesian estimation of vancomycin drug exposure (AUC), the predictive performance was generally most accurate with sample collection between 1.5 and 6 h after infusion, though optimal sampling times varied across different population PK models.
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Affiliation(s)
- Rashmi V Shingde
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Stephanie E Reuter
- School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Garry G Graham
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
- School of Medical Science, University of New South Wales, Kensington, NSW, Australia
| | - Jane E Carland
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
- St Vincent’s Clinical School, University of New South Wales, Kensington, NSW, Australia
| | - Kenneth M Williams
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
- School of Medical Science, University of New South Wales, Kensington, NSW, Australia
| | - Richard O Day
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
- School of Medical Science, University of New South Wales, Kensington, NSW, Australia
- St Vincent’s Clinical School, University of New South Wales, Kensington, NSW, Australia
| | - Sophie L Stocker
- Department of Clinical Pharmacology & Toxicology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
- St Vincent’s Clinical School, University of New South Wales, Kensington, NSW, Australia
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23
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Menz BD, Stocker SL, Verougstraete N, Kocic D, Galettis P, Stove CP, Reuter SE. Barriers and opportunities for the clinical implementation of therapeutic drug monitoring in oncology. Br J Clin Pharmacol 2020; 87:227-236. [PMID: 32430968 DOI: 10.1111/bcp.14372] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 12/12/2022] Open
Abstract
There are few fields of medicine in which the individualisation of medicines is more important than in the area of oncology. Under-dosing can have significant ramifications due to the potential for therapeutic failure and cancer progression; by contrast, over-dosing may lead to severe treatment-limiting side effects, such as agranulocytosis and neutropenia. Both circumstances lead to poor patient prognosis and contribute to the high mortality rates still seen in oncology. The concept of dose individualisation tailors dosing for each individual patient to ensure optimal drug exposure and best clinical outcomes. While the value of this strategy is well recognised, it has seen little translation to clinical application. However, it is important to recognise that the clinical setting of oncology is unlike that for which therapeutic drug monitoring (TDM) is currently the cornerstone of therapy (e.g. antimicrobials). Whilst there is much to learn from these established TDM settings, the challenges presented in the treatment of cancer must be considered to ensure the implementation of TDM in clinical practice. Recent advancements in a range of scientific disciplines have the capacity to address the current system limitations and significantly enhance the use of anticancer medicines to improve patient health. This review examines opportunities presented by these innovative scientific methodologies, specifically sampling strategies, bioanalytics and dosing decision support, to enable optimal practice and facilitate the clinical implementation of TDM in oncology.
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Affiliation(s)
- Bradley D Menz
- SA Pharmacy, Flinders Medical Centre, Adelaide, SA, Australia
| | - Sophie L Stocker
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Nick Verougstraete
- Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium.,Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Danijela Kocic
- Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Sydney, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Peter Galettis
- Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Christophe P Stove
- Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Stephanie E Reuter
- UniSA Clinical & Health Sciences, University of South Australia, Adelaide, SA, Australia
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24
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Milliken E, de Zwart AES, Alffenaar JWC, Marriott DJE, Riezebos-Brilman A, Schteinman A, Evans AM, Glanville AR, Verschuuren EAM, Reuter SE. Population pharmacokinetics of ribavirin in lung transplant recipients and examination of current and alternative dosing regimens. J Antimicrob Chemother 2020; 74:691-698. [PMID: 30452661 DOI: 10.1093/jac/dky466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 09/29/2018] [Accepted: 10/13/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Ribavirin is used in the treatment of respiratory paramyxovirus infection in lung transplant recipients; however, its pharmacokinetic profile in the transplant population is unknown despite the potential for alterations due to underlying pathology. Furthermore, the ability of current regimens to meet exposure targets has not been established. OBJECTIVES This study examined the pharmacokinetics of ribavirin in a lung transplant population for which current and alternative dosing regimens were assessed. METHODS Population pharmacokinetic modelling was conducted in NONMEM using concentration-time data from 24 lung transplant recipients and 6 healthy volunteers. Monte Carlo simulation was used to assess the ability of dosing regimens to achieve pre-specified target concentrations. RESULTS AND CONCLUSIONS A three-compartment model with first-order elimination most adequately described ribavirin concentration-time data, with CLCR and patient type (i.e. lung transplant) identified as significant covariates in the model. Simulations indicate that current regimens achieve efficacious concentrations within 24 h of treatment initiation that increase to supra-therapeutic levels over the treatment period. A regimen of 8 mg/kg q6h orally for 48 h followed by 8 mg/kg q24h orally for the remainder of the treatment period was predicted to result in >90% of patients exhibiting concentrations within the defined target range throughout the entire treatment course. Additional work to formally establish target therapeutic concentrations is required; however, this study provides a valuable first step in determining optimal ribavirin treatment regimens for paramyxovirus infections in the lung transplant population.
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Affiliation(s)
- Eliza Milliken
- Faculty of Medicine, The University of Notre Dame, Sydney, Australia
| | - Auke E S de Zwart
- University of Groningen, University Medical Centre Groningen, Department of Pulmonary Diseases and Tuberculosis, Groningen, The Netherlands
| | - Jan-Willem C Alffenaar
- University of Groningen, University Medical Centre Groningen, Department of Clinical Pharmacy and Pharmacology, Groningen, The Netherlands
| | | | - Annelies Riezebos-Brilman
- Department of Medical Microbiology, University Medical Centre Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Ana Schteinman
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, Australia.,St Vincent's Clinical School, UNSW Medicine, University of New South Wales, Sydney, Australia
| | - Allan M Evans
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Allan R Glanville
- Faculty of Medicine, The University of Notre Dame, Sydney, Australia.,Department of Thoracic Medicine, St Vincent's Hospital, Sydney, Australia
| | - Erik A M Verschuuren
- University of Groningen, University Medical Centre Groningen, Department of Pulmonary Diseases and Tuberculosis, Groningen, The Netherlands
| | - Stephanie E Reuter
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.,School of Medicine and Public Health, The University of Newcastle, Newcastle, Australia
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25
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Hughes JH, Upton RN, Reuter SE, Phelps MA, Foster DJR. Optimising time samples for determining area under the curve of pharmacokinetic data using non-compartmental analysis. J Pharm Pharmacol 2019; 71:1635-1644. [DOI: 10.1111/jphp.13154] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/20/2019] [Indexed: 12/01/2022]
Abstract
Abstract
Objectives
The selection of sample times for a pharmacokinetic study is important when trapezoidal integration (e.g. non-compartmental analysis) is used to determine the area under the concentration–time curve (AUC). The aim of this study was to develop an algorithm that determines optimal times that provide the most accurate AUC by minimising trapezoidal integration error.
Methods
The algorithm required initial single individual or mean pooled concentration data but did not specifically require a prior pharmacokinetic model. Optimal sample intervals were determined by minimising trapezoidal error using a genetic algorithm followed by a quasi-Newton method. The method was evaluated against simulated and clinical datasets to determine the method's ability to estimate the AUC.
Key findings
The sample times produced by the algorithm were able to accurately estimate the AUC of pharmacokinetic profiles, with the relative AUC having 90% confidence intervals of 0.919–1.05 for profiles with two-compartment kinetics. When comparing the algorithm with rich sampling (e.g. phase I trial), the algorithm provided equivalent or superior sample times with fewer observations.
Conclusions
The creation of the algorithm and its companion web application allows users with limited pharmacometric or programming training can obtain optimal sampling times for pharmacokinetic studies.
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Affiliation(s)
- Jim H Hughes
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Richard N Upton
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Stephanie E Reuter
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Mitch A Phelps
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - David J R Foster
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
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26
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Hughes JH, Phelps MA, Upton RN, Reuter SE, Gao Y, Byrd JC, Grever MR, Hofmeister CC, Marcucci G, Blum W, Blum KA, Foster DJR. Population pharmacokinetics of lenalidomide in patients with B-cell malignancies. Br J Clin Pharmacol 2019; 85:924-934. [PMID: 30672004 DOI: 10.1111/bcp.13873] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/09/2019] [Accepted: 01/14/2019] [Indexed: 12/11/2022] Open
Abstract
AIMS Lenalidomide is an immunomodulatory imide drug used broadly in the treatment of multiple myeloma and lymphoma. It continues to be evaluated in chronic lymphocytic leukaemia (CLL) at lower doses due to dose-related toxicities including tumour flare and tumour lysis syndrome. This study aimed to develop a population pharmacokinetic model for lenalidomide in multiple cancers, including CLL, to identify any disease-related differences in disposition. METHODS Lenalidomide concentrations from 4 clinical trials were collated (1999 samples, 125 subjects), covering 4 cancers (multiple myeloma, CLL, acute myeloid leukaemia and acute lymphoblastic leukaemia) and a large dose range (2.5-75 mg). A population pharmacokinetic model was developed with NONMEM and patient demographics were tested as covariates. RESULTS The data were best fitted by a 1-compartment kinetic model with absorption described by 7 transit compartments. Clearance and volume of distribution were allometrically scaled for fat-free mass. The population parameter estimates for apparent clearance, apparent volume of distribution and transit rate constant were 12 L/h (10.8-13.6), 68.8 L (61.8-76.3), and 13.5 h-1 (11.9-36.8) respectively. Patients with impaired renal function (creatinine clearance <30 mL/min) exhibited a 22% reduction in lenalidomide clearance compared to patients with creatinine clearance of 90 mL/min. Cancer type had no discernible effect on lenalidomide disposition. CONCLUSIONS This is the first report of a lenalidomide population pharmacokinetic model to evaluate lenalidomide pharmacokinetics in patients with CLL and compare its pharmacokinetics with other B-cell malignancies. As no differences in pharmacokinetics were found between the observed cancer-types, the unique toxicities observed in CLL may be due to disease-specific pharmacodynamics.
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Affiliation(s)
- Jim H Hughes
- Australian Centre for Pharmacometrics, School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Australia
| | - Mitch A Phelps
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - Richard N Upton
- Australian Centre for Pharmacometrics, School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Australia
| | - Stephanie E Reuter
- School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Australia
| | - Yue Gao
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - John C Byrd
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Michael R Grever
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Craig C Hofmeister
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Guido Marcucci
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - William Blum
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Kristie A Blum
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.,Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - David J R Foster
- Australian Centre for Pharmacometrics, School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Australia
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Reuter SE, Evans AM, Ward MB. Reducing Palivizumab Dose Requirements Through Rational Dose Regimen Design. CPT Pharmacometrics Syst Pharmacol 2018; 8:26-33. [PMID: 30426719 PMCID: PMC6363066 DOI: 10.1002/psp4.12364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 10/09/2018] [Indexed: 02/02/2023]
Abstract
Palivizumab for respiratory syncytial virus (RSV) immunoprophylaxis in premature infants poses a significant economic challenge. Although standard dosing of palivizumab results in unnecessary drug accumulation without additional clinical benefit, some clinicians have moved outside of evidence‐based practice by implementing untested dose modifications, potentially jeopardizing efficacy. Using an industry‐developed population pharmacokinetic model, this study evaluated the previously published alternate dosing regimens and developed a revised regimen that minimizes palivizumab dose requirements while maintaining established therapeutic concentrations. All published dose modifications resulted in unacceptably high proportions of infants not attaining minimum protective concentrations, compromising efficacy. Through intelligent dose regimen design, a clinically practical palivizumab regimen was devised that reduces drug use by 25%, while enabling a greater proportion of infants attaining early season target concentrations, particularly those at greatest risk of the consequences of RSV infection. This novel regimen has the potential to substantially change clinical practice and increase drug availability.
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Affiliation(s)
- Stephanie E Reuter
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Allan M Evans
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Michael B Ward
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
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Lucas CJ, Galettis P, Song S, Solowij N, Reuter SE, Schneider J, Martin JH. Cannabinoid Disposition After Human Intraperitoneal Use: AnInsight Into Intraperitoneal Pharmacokinetic Properties in Metastatic Cancer. Clin Ther 2018; 40:1442-1447. [PMID: 29317112 DOI: 10.1016/j.clinthera.2017.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 11/15/2017] [Accepted: 12/14/2017] [Indexed: 11/19/2022]
Abstract
BACKGROUND Medicinal cannabis is prescribed under the provision of a controlled drug in the Australian Poisons Standard. However, multiple laws must be navigated in order for patients to obtain access and imported products can be expensive. Dose-response information for both efficacy and toxicity pertaining to medicinal cannabis is lacking. The pharmacokinetic properties of cannabis administered by traditional routes has been described but to date, there is no literature on the pharmacokinetic properties of an intraperitoneal cannabinoid emulsion. CASE DESCRIPTION A cachectic 56-year-old female with stage IV ovarian cancer and peritoneal metastases presented to hospital with fevers, abdominal distension and severe pain, vomiting, anorexia, dehydration and confusion. The patient reported receiving an intraperitoneal injection, purported to contain 12g of mixed cannabinoid (administered by a deregistered medical practitioner) two days prior to presentation. Additionally, cannabis oil oral capsules were administered in the hours prior to hospital admission. RESULTS THC concentrations were consistent with the clinical state but not with the known pharmacokinetic properties of cannabis nor of intraperitoneal absorption. THC concentrations at the time of presentation were predicted to be ~60ng/mL. Evidence suggests that blood THC concentrations >5ng/mL are associated with substantial cognitive and psychomotor impairment. The predicted time for concentrations to drop <5ng/mL was 49days after administration. DISCUSSION The unusual pharmacokinetic properties of the case suggest that there is a large amount unknown about cannabis pharmacokinetic properties. The pharmacokinetic properties of a large amount of a lipid soluble compound given intraperitoneally gave insights into the absorption and distribution of cannabinoids, particularly in the setting of metastatic malignancy.
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Affiliation(s)
- Catherine J Lucas
- Discipline of Clinical Pharmacology, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia.
| | - Peter Galettis
- Discipline of Clinical Pharmacology, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia
| | - Shuzhen Song
- Drug/Trace Metal Lab, Chemistry Department, Pathology North Hunter, New South Wales, Australia
| | - Nadia Solowij
- School of Psychology and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | - Stephanie E Reuter
- Discipline of Clinical Pharmacology, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia; School of Pharmacy and Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
| | - Jennifer Schneider
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Jennifer H Martin
- Discipline of Clinical Pharmacology, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia
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Reuter SE, Upton RN, Evans AM, Navaratnam V, Olliaro PL. Population pharmacokinetics of orally administered mefloquine in healthy volunteers and patients with uncomplicated Plasmodium falciparum malaria. J Antimicrob Chemother 2014; 70:868-76. [PMID: 25377567 DOI: 10.1093/jac/dku430] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The determination of dosing regimens for the treatment of malaria is largely empirical and thus a better understanding of the pharmacokinetic/pharmacodynamic properties of antimalarial agents is required to assess the adequacy of current treatment regimens and identify sources of suboptimal dosing that could select for drug-resistant parasites. Mefloquine is a widely used antimalarial, commonly given in combination with artesunate. PATIENTS AND METHODS Mefloquine pharmacokinetics was assessed in 24 healthy adults and 43 patients with Plasmodium falciparum malaria administered mefloquine in combination with artesunate. Population pharmacokinetic modelling was conducted using NONMEM. RESULTS A two-compartment model with a single transit compartment and first-order elimination from the central compartment most adequately described mefloquine concentration-time data. The model incorporated population parameter variability for clearance (CL/F), central volume of distribution (VC/F) and absorption rate constant (KA) and identified, in addition to body weight, malaria infection as a covariate for VC/F (but not CL/F). Monte Carlo simulations predict that falciparum malaria infection is associated with a shorter elimination half-life (407 versus 566 h) and T>MIC (766 versus 893 h). CONCLUSIONS This is the first known population pharmacokinetic study to show falciparum malaria to influence mefloquine disposition. Protein binding, anaemia and other factors may contribute to differences between healthy individuals and patients. As VC/F is related to the earlier portion of the concentration-time profiles, which occurs during acute malaria, and CL/F is more related to the terminal phase during convalescence after treatment, this may explain why malaria was found to be a covariate for VC/F but not CL/F.
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Affiliation(s)
- Stephanie E Reuter
- School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, SA, Australia Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Richard N Upton
- School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, SA, Australia Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Allan M Evans
- School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, SA, Australia Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Visweswaran Navaratnam
- Centre for Drug Research, Universiti Sains Malaysia, Penang, Malaysia Postgraduate, Research and Strategic Development, Taylor's University, Selangor, Malaysia
| | - Piero L Olliaro
- UNICEF/UNDP/World Bank/WHO Special Programme for Research & Training in Tropical Diseases (TDR), Geneva, Switzerland Centre for Tropical Medicine and Vaccinology, Nuffield Department of Medicine, University of Oxford, Churchill Hospital, Oxford, UK
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Reuter SE, Evans AM. What is the value of
l
‐carnitine level determination for carnitine supplementation in hemodialysis patients? Hemodial Int 2013; 17:335-8. [DOI: 10.1111/hdi.12021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
L-Carnitine (levocarnitine) is a naturally occurring compound found in all mammalian species. The most important biological function of L-carnitine is in the transport of fatty acids into the mitochondria for subsequent β-oxidation, a process which results in the esterification of L-carnitine to form acylcarnitine derivatives. As such, the endogenous carnitine pool is comprised of L-carnitine and various short-, medium- and long-chain acylcarnitines. The physiological importance of L-carnitine and its obligatory role in the mitochondrial metabolism of fatty acids has been clearly established; however, more recently, additional functions of the carnitine system have been described, including the removal of excess acyl groups from the body and the modulation of intracellular coenzyme A (CoA) homeostasis. In light of this, acylcarnitines cannot simply be considered by-products of the enzymatic carnitine transfer system, but provide indirect evidence of altered mitochondrial metabolism. Consequently, examination of the contribution of L-carnitine and acylcarnitines to the endogenous carnitine pool (i.e. carnitine pool composition) is critical in order to adequately characterize metabolic status. The concentrations of L-carnitine and its esters are maintained within relatively narrow limits for normal biological functioning in their pivotal roles in fatty acid oxidation and maintenance of free CoA availability. The homeostasis of carnitine is multifaceted with concentrations achieved and maintained by a combination of oral absorption, de novo biosynthesis, carrier-mediated distribution into tissues and extensive, but saturable, renal tubular reabsorption. Various disorders of carnitine insufficiency have been described but ultimately all result in impaired entry of fatty acids into the mitochondria and consequently disturbed lipid oxidation. Given the sensitivity of acylcarnitine concentrations and the relative carnitine pool composition in reflecting the intramitochondrial acyl-CoA to free CoA ratio (and, hence, any disturbances in mitochondrial metabolism), the relative contribution of L-carnitine and acylcarnitines within the total carnitine pool is therefore considered critical in the identification of mitochondria dysfunction. Although there is considerable research in the literature focused on disorders of carnitine insufficiency, relatively few have examined relative carnitine pool composition in these conditions; consequently, the complexity of these disorders may not be fully understood. Similarly, although important studies have been conducted establishing the pharmacokinetics of exogenous carnitine and short-chain carnitine esters in healthy volunteers, few studies have examined carnitine pharmacokinetics in patient groups. Furthermore, the impact of L-carnitine administration on the kinetics of acylcarnitines has not been established. Given the importance of L-carnitine as well as acylcarnitines in maintaining normal mitochondrial function, this review seeks to examine previous research associated with the homeostasis and pharmacokinetics of L-carnitine and its esters, and highlight potential areas of future research.
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Affiliation(s)
- Stephanie E Reuter
- School of Pharmacy Medical Sciences, University of South Australia, Adelaide, SA, Australia.
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Wiese MD, Sluggett JK, Wilson CJ, Reuter SE, Turner SC, Evans AM. Perceived and actual paracetamol dosing in overweight and obese children. Eur J Hosp Pharm 2012. [DOI: 10.1136/ejhpharm-2011-000031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Reuter SE, Evans AM, Steiber AL. Effectiveness of l-carnitine supplementation in patients with erythropoietin-resistant anemia. Kidney Res Clin Pract 2012. [DOI: 10.1016/j.krcp.2012.04.555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Reuter SE, Evans AM. Long-chain acylcarnitine deficiency in patients with chronic fatigue syndrome. Potential involvement of altered carnitine palmitoyltransferase-I activity. J Intern Med 2011; 270:76-84. [PMID: 21205027 DOI: 10.1111/j.1365-2796.2010.02341.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The underlying aetiology of chronic fatigue syndrome is currently unknown; however, in the light of carnitine's critical role in mitochondrial energy production, it has been suggested that chronic fatigue syndrome may be associated with altered carnitine homeostasis. This study was conducted to comparatively examine full endogenous carnitine profiles in patients with chronic fatigue syndrome and healthy controls. DESIGN A cross-sectional, observational study. SETTING AND SUBJECTS Forty-four patients with chronic fatigue syndrome and 49 age- and gender-matched healthy controls were recruited from the community and studied at the School of Pharmacy & Medical Sciences, University of South Australia. MAIN OUTCOME MEASURES All participants completed a fatigue severity scale questionnaire and had a single fasting blood sample collected which was analysed for l-carnitine and 35 individual acylcarnitine concentrations in plasma by LC-MS/MS. RESULTS Patients with chronic fatigue syndrome exhibited significantly altered concentrations of C8:1, C12DC, C14, C16:1, C18, C18:1, C18:2 and C18:1-OH acylcarnitines; of particular note, oleyl-L-carnitine (C18:1) and linoleyl-L-carnitine (C18:2) were, on average, 30-40% lower in patients than controls (P < 0.0001). Significant correlations between acylcarnitine concentrations and clinical symptomology were also demonstrated. CONCLUSIONS It is proposed that this disturbance in carnitine homeostasis is reflective of a reduction in carnitine palmitoyltransferase-I (CPT-I) activity, possibly a result of the accumulation of omega-6 fatty acids previously observed in this patient population. It is hypothesized that the administration of omega-3 fatty acids in combination with l-carnitine would increase CPT-I activity and improve chronic fatigue syndrome symptomology.
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Affiliation(s)
- S E Reuter
- From the School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, SA, Australia.
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Reuter SE, Faull RJ, Ranieri E, Evans AM. Endogenous plasma carnitine pool composition and response to erythropoietin treatment in chronic haemodialysis patients. Nephrol Dial Transplant 2008; 24:990-6. [PMID: 18987259 DOI: 10.1093/ndt/gfn588] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Anaemia is a common complication associated with haemodialysis and is usually managed by treatment with recombinant human erythropoietin (rHuEPO). However, many patients remain hyporesponsive to rHuEPO treatment despite adequate iron therapy. The effect of L-carnitine administration on rHuEPO dose and/or haematocrit in haemodialysis patients has been previously reported with equivocal results. This study examined the relationship between endogenous carnitine pool composition and rHuEPO requirements in long-term haemodialysis patients. METHODS Pre-dialysis blood samples were collected from 87 patients and analysed for plasma L-carnitine and individual acylcarnitine levels by LCMS/MS. As an indication of rHuEPO responsiveness, erythropoietin resistance index (ERI) was calculated as rHuEPO dose/kg/week normalized for haemoglobin levels. RESULTS A significant negative correlation between L-carnitine levels and ERI was found (P = 0.0421). All patients categorized as high ERI (>0.02 microg/kg/week/gHb) exhibited subnormal L-carnitine levels (<30 microM); conversely, patients with normal L-carnitine levels (>30 microM) displayed low ERI values (<0.02 microg/kg/week/gHb). More importantly, the ratio of non-acetyl acylcarnitines/total carnitine was significantly positively correlated with ERI (P = 0.0062). CONCLUSIONS These data illustrate the relationship between carnitine levels and response to rHuEPO treatment in haemodialysis patients, in particular, the importance of the proportion of long-chain acylcarnitines within the plasma carnitine pool. This proportion may be more indicative of the response to L-carnitine supplementation than absolute L-carnitine levels alone.
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Affiliation(s)
- Stephanie E Reuter
- Sansom Institute, University of South Australia, Adelaide, SA, Australia
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Abstract
BACKGROUND l-carnitine is an endogenous substance, vital in the transport of fatty acids across the inner mitochondrial membrane for oxidation. Disturbances in carnitine homeostasis can have a significant impact on human health; therefore, it is critical to define normal endogenous concentrations for l-carnitine and its esters to facilitate the diagnosis of carnitine deficiency disorders. This study was conducted to determine the normal concentrations of a number of carnitines in healthy adults using three analytical methods. The impact of age and gender on carnitine concentrations was also examined. METHODS Blood samples were collected from 60 healthy subjects of both genders and various ages. Plasma samples were analysed for endogenous carnitine concentrations by radioenzymatic assay, high-performance liquid chromatography and electrospray tandem mass spectrometry. RESULTS Precision and accuracy of results obtained for each assay were within acceptable limits. Average endogenous concentrations obtained from the three analytical methods in this study were in the range of 38-44, 6-7 and 49-50 mumol/L for l-carnitine, acetyl-l-carnitine and total carnitine, respectively. Comparison of results between the genders indicated that males had significantly higher endogenous plasma l-carnitine and total carnitine concentrations than females. Age was found to have no impact on plasma carnitine concentrations. CONCLUSION These results are useful in the evaluation of biochemical or metabolic disturbances and in the diagnosis and treatment of patients with carnitine deficiency.
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Affiliation(s)
- Stephanie E Reuter
- Sansom Institute, University of South Australia, Adelaide, SA, Australia
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Abstract
It has been widely established that patients with end-stage renal disease undergoing chronic haemodialysis therapy exhibit low endogenous levels of L-carnitine and elevated acylcarnitine levels; however, the clinical implication of this altered carnitine profile is not as clear. It has been suggested that these disturbances in carnitine homeostasis may be associated with a number of clinical problems common in this patient population, including erythropoietin-resistant anaemia, cardiac dysfunction, and dialytic complications such as hypotension, cramps and fatigue. In January 2003, the Centers for Medicare and Medicaid Services (USA) implemented coverage of intravenous L-carnitine for the treatment of erythropoietin-resistant anaemia and/or intradialytic hypotension in patients with low endogenous L-carnitine concentrations. It has been estimated that in the period of 1998-2003, 3.8-7.2% of all haemodialysis patients in the USA received at least one dose of L-carnitine, with 2.7-5.2% of patients receiving at least 3 months of supplementation for one or both of these conditions. The use of L-carnitine within Australia is virtually non-existent, which leads us to the question: Are Australian haemodialysis patients missing out? This review examines the previous research associated with L-carnitine administration to chronic dialysis patients for the treatment of anaemia, cardiac dysfunction, dyslipidaemia and/or dialytic symptoms, and discusses whether supplementation is warranted within the Australian setting.
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Affiliation(s)
- Stephanie E Reuter
- Sansom Institute, University of South Australia, and Department of Renal Medicine, Royal Adelaide Hospital, South Australia, Australia
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Reuter SE, Evans AM, Faull RJ, Chace DH, Fornasini G. Impact of haemodialysis on individual endogenous plasma acylcarnitine concentrations in end-stage renal disease. Ann Clin Biochem 2005; 42:387-93. [PMID: 16168195 DOI: 10.1258/0004563054889954] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Patients with end-stage renal disease (ESRD) undergoing long-term haemodialysis exhibit low L-carnitine and elevated acylcarnitine concentrations. This study evaluated endogenous concentrations of an array of acylcarnitines (carbon chain length up to 18) in healthy individuals and ESRD patients receiving haemodialysis, and examined the impact of a single haemodialysis session on acylcarnitine concentrations. METHODS Blood samples were collected from 60 healthy subjects and 50 ESRD patients undergoing haemodialysis (pre- and post-dialysis samples). Plasma samples were analysed for individual acylcarnitine concentrations by electrospray MS/MS. RESULTS Of the 31 acylcarnitines, 29 were significantly (P<0.05) elevated in ESRD patients compared with healthy controls; in particular, C5 and C8:1 concentrations were substantially elevated. For acylcarnitines with a carbon chain length less than eight, plasma acylcarnitine concentrations decreased significantly over the course of a single dialysis session; however, post-dialysis concentrations invariably remained significantly higher than those in healthy subjects. Dialytic removal of acylcarnitines diminished once the acyl chain length exceeded eight carbons. CONCLUSIONS The accumulation of acylcarnitines during long-term haemodialysis suggests that removal by haemodialysis is less efficient than removal from the body by the healthy kidney. Removal is significantly correlated to acyl chain length, most likely due to the increased molecular weight and lipophilicity that accompanies increased chain length.
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Affiliation(s)
- Stephanie E Reuter
- Centre for Pharmaceutical Research, University of South Australia, North Terrace, Adelaide, SA 5000, Australia
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Reuter SE, Evans AM, Fornasini G. Reply from the Authors. Kidney Int 2005. [DOI: 10.1038/ki.2005.4496223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Evans AM, Faull RJ, Nation RL, Prasad S, Elias T, Reuter SE, Fornasini G. Impact of hemodialysis on endogenous plasma and muscle carnitine levels in patients with end-stage renal disease. Kidney Int 2004; 66:1527-34. [PMID: 15458447 DOI: 10.1111/j.1523-1755.2004.00916.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND End-stage renal disease (ESRD) patients undergoing hemodialysis treatment have reduced plasma L-carnitine levels; however, the relationship between dialysis age and carnitine status is poorly understood. This study examined the relationship between duration of dialysis and plasma and skeletal muscle concentrations of L-carnitine and its esters in ESRD patients. METHODS Blood samples were collected from 21 patients at baseline and throughout the first 12 months of hemodialysis. In 5 patients, muscle samples were obtained after 0, 6, and 12 months of hemodialysis. Blood and muscle samples were collected from an additional 20 patients with a mean dialysis age of 5.10 years. L-carnitine, acetyl-L-carnitine, and total L-carnitine were measured by high-performance liquid chromatography (HPLC). RESULTS The mean +/- SD plasma L-carnitine concentration in ESRD patients who had not yet started hemodialysis was 50.6 +/- 20.0 micromol/L. Significantly lower concentrations were observed after 12 months (29.7 +/- 10.5 micromol/L) and >12 months (22.0 +/- 5.4 micromol/L) of hemodialysis treatment. Acetyl-L-carnitine also declined with dialysis age, while plasma nonacetylated acylcarnitines continued to increase with the progression of hemodialysis therapy. An inverse relationship between dialysis age and muscle L-carnitine concentrations was observed. CONCLUSION Long-term hemodialysis treatment is associated with a significant reduction in endogenous plasma and muscle L-carnitine levels and a significant increase in plasma acylcarnitines. The majority of the change in plasma L-carnitine concentrations occurs within the first few months of hemodialysis, while muscle levels continue to decline after 12 months of treatment.
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Affiliation(s)
- Allan M Evans
- Centre for Pharmaceutical Research, School of Pharmaceutical, Molecular and Biomedical Sciences, University of South Australia, Adelaide, South Australia, Australia.
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