Simultaneous quantitation of azole antifungals, antibiotics, imatinib, and raltegravir in human plasma by two-dimensional high-performance liquid chromatography–tandem mass spectrometry

The role of residual (veterinary) antibiotics in chemical exposome analysis: Current progress and future perspectives

Humans are exposed to a complex mixture of environmental and food-related chemicals throughout their lifetime. Exposome research intends to explore the nongenetic, that is, environmental causes of chronic disease and their interactions comprehensively. Residual antibiotics can enter the human body through therapeutics, foods of animal origin, aquatic products, or drinking water. In the last decade, significant levels of residual antibiotics in human urine have been described, demonstrating frequent exposure throughout populations. To which extent they contribute to human health risks is debated. Human biomonitoring (HBM) aims to determine and quantify concentrations of xenobiotics in human specimens and provides the toolbox to monitor exposure to diverse chemical exposures. Due to their public health implications, priority-listed xenobiotics are routinely monitored in the European Union and other countries. However, antibiotics, an important class of (food-derived) xenobiotics, are still not systematically investigated for a better and more holistic understanding in the context of exposomics. This review provides a comprehensive summary of HBM research related to antibiotics, existing liquid chromatography-mass spectrometry (LC-MS)-based analytical methods, and potential health risks caused by unintended exposure. Incorporating antibiotics into the chemical exposome framework through routine HBM using multiclass analytical methods will provide a better understanding of the toxicological or pharmacological mixture effects and, ultimately, the chemical exposome.

Recent Trends in Therapeutic Drug Monitoring of Peptide Antibiotics

Antimicrobial peptides take a specific position in the field of antibiotics (ATBs), however, from a large number of available molecules only a few of them were approved and are used in clinics. These therapeutic modalities play a crucial role in the management of diseases caused by multidrug-resistant bacterial pathogens and represent the last-line therapy for bacterial infections. Therefore, there is a demand for a rationale use of such ATBs based on optimization of the dosing strategy to minimize the risk of resistance and ensure the sustainable efficacy of the drug in real clinical practice. Therapeutic drug monitoring, as a measurement of drug concentration in the body fluids or tissues, results in the optimization of the patient´s medication and therapy outcome. This strategy is beneficial and could result in tailored therapy for different types of infection and the prolongation of the use and efficacy of ATBs in hospitals. This review paper provides an actual overview of approved antimicrobial peptides used in clinical practice and covers current trends in their analysis by convenient and advanced methodologies used for their identification and/or quantitation in biological matrices for therapeutic drug monitoring purposes. Special emphasis is given to the methods with perspective clinical outcomes.

Simultaneous determination of three tyrosine kinase inhibitors and three triazoles in human plasma by LC-MS/MS: applications to therapeutic drug monitoring and drug-drug interaction studies

Tyrosine kinase inhibitors (TKIs) and triazole antifungals are the first-line drugs for treating chronic myeloid leukemia (CML) and fungal infections, respectively, but both suffer from large exposure differences and narrow therapeutic windows. Moreover, these two types of drugs are commonly used together in CML patients with fungal infections. Multiple studies and guidelines have suggested the importance of therapeutic drug monitoring (TDM) of TKIs and triazoles. Currently, methods for the simultaneous determination of both types of drugs are limited. We developed a simple, rapid, and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of three commonly used TKIs (imatinib, dasatinib, and nilotinib) and three commonly used triazoles (voriconazole, itraconazole, and posaconazole) in human plasma. The analytes were eluted on a Welch XB-C18 analytical column (50 × 2.1 mm, 5 µm) at 0.7 mL/min, using a gradient elution of 10 mM ammonium formate (A) and methanol-acetonitrile-isopropanol (80:10:10, v/v/v) containing 0.2 % formic acid (B) with a total analysis time of 3.5 min. The calibration curves were linear over the range from 20 to 4000 ng/mL for imatinib and nilotinib, from 2 to 400 ng/mL for dasatinib, and from 50 to 10,000 ng/mL for voriconazole, itraconazole, and posaconazole. Selectivity, accuracy, precision, recovery, matrix effect, and stability all met the validation requirements. The method was successfully used for TDM in CML patients who co-treated with both TKIs and triazoles. Drug-drug interaction analysis between TKIs and triazoles showed that a significant positive correlation was observed between imatinib and voriconazole, as well as dasatinib and voriconazole. Therefore, this method can be well applied in clinical TDM for patients receiving TKIs, triazoles, or both simultaneously.

Preanalytical Stability of 13 Antibiotics in Biological Samples: A Crucial Factor for Therapeutic Drug Monitoring

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, -20 °C, and -80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze-thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2-8 °C should be limited to a maximum of 24 h, and storage at -20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at -80 °C is suggested.

Progress of triazole antifungal agent posaconazole in individualized therapy

WHAT IS KNOWN AND OBJECTIVE

Posaconazole is the second-generation triazole antifungal agent with widespread clinical application. Posaconazole exposure is influenced by various factors such as drug interactions, disease state and diet, resulting in a high interindividual variability in many patients and failure to ensure therapeutic efficacy. Therefore, it is necessary to conduct individualized therapy on posaconazole to ensure the efficacy and safety of treatment.

METHODS

Articles were identified through PubMed using the keywords such as "posaconazole," "therapeutic drug monitoring" and "Population pharmacokinetics" from 1 January 2001 to 30 April 2022.

RESULTS AND DISCUSSION

In this paper, we review the individualized treatment studies of posaconazole from the three aspects of therapeutic drug monitoring, population pharmacokinetic study and Monte Carlo simulation to provide reference for in-depth individualized posaconazole dosing studies.

WHAT IS NEW AND CONCLUSION

This review suggests that therapeutic drug monitoring should be performed in patients taking posaconazole to adjust the dosage and assess the efficacy and cost-effectiveness of posaconazole under different clinical conditions and different dosing regimens through Monte Carlo simulations. In the future, a more detailed delineation and comprehensive examination of posaconazole PPK for specific populations requires further study.

Variability of Isavuconazole Trough Concentrations during Longitudinal Therapeutic Drug Monitoring

Isavuconazole (ISA), a triazole antifungal agent, is licensed for the treatment of invasive aspergillosis and mucormycosis. Therapeutic drug monitoring (TDM) is a cornerstone of treatment efficacy for triazole antifungals due to their pharmacokinetic variability, except for ISA, for which the utility of TDM is still uncertain. We performed a retrospective study that aimed to assess the inter- and intra-individual variability of ISA trough concentrations (Cmin) and to identify the determinants involved in such variability. ISA Cmin measured in adult patients at the Grenoble Alpes University Hospital between January 2018 and August 2020 were retrospectively analyzed. In total, 304 ISA Cmin for 33 patients were analyzed. The median ISA Cmin was 2.8 [25th−75th percentiles: 2.0−3.7] mg/L. The inter- and intra-individual variability was 41.5% and 30.7%, respectively. Multivariate analysis showed independent covariate effects of dose (β = 0.004 ± 3.56 × 10−4, p < 0.001), Aspartate aminotransférase (ASAT) (β = 0.002 ± 5.41 × 10−4, p = 0.002), and protein levels (β = 0.022 ± 0.004, p < 0.001) on ISA Cmin, whereas C reactive protein levels did not show any association. This study, conducted on a large number of ISA Cmin, shows that ISA exposure exhibits variability, explained in part by the ISA dose, and ASAT and protein levels.

A Pathophysiological Approach To Current Biomarkers

Biomarkers are necessary for screening and diagnosing numerous diseases, predicting the prognosis of patients, and following-up treatment and the course of the patient. Everyday new biomarkers are being used in clinics for these purposes. This section will discuss the physiological roles of the various current biomarkers in a healthy person and the pathophysiological mechanisms underlying the release of these biomarkers. This chapter aims to gain a new perspective for evaluating and interpreting the most current biomarkers.

Effects of inflammation on voriconazole levels: a systematic review

AIMS

This study aimed to review the studies evaluating the effect of the inflammatory state on voriconazole (VRZ) levels.

METHODS

The study included randomized clinical trials, cohort studies, and case-control studies that focused on the influence of the inflammatory state on VRZ levels. Following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, relevant articles published until 2021 were searched in several databases, including PubMed, Embase, Web of Science, and the Cochrane Library.

RESULTS

Twenty studies were included in this review, of which 15 described adult populations, 3 described pediatric populations, and 2 included both adult and pediatric populations. Seventeen studies used C-reactive protein (CRP) as an indicator of inflammation, 6 described a dose-response relationship for the effect of inflammation represented by CRP on VRZ concentrations, and 4 examined the effect of CRP on the metabolic rate of VRZ.

CONCLUSIONS

Our findings showed that the level of inflammation can significantly affect VRZ levels. However, the effect of inflammation on VRZ concentrations in children is controversial and must be analyzed along with age. Clinicians dosing VRZ should take into account the patient's inflammatory state. The impact of inflammation on genotype-based dosing decisions requires further study to explain the high pharmacokinetic variability of VRZ.

Therapeutic drug monitoring and CYP2C19 genotyping guide the application of voriconazole in children

BACKGROUND

This study used therapeutic drug monitoring (TDM) and CYP2C19 gene polymorphism analysis to explore the efficacy and safety of different doses of voriconazole (VCZ) for the clinical treatment of pediatric patients, with the aim of providing guidelines for individualized antifungal therapy in children.

METHODS

Our study enrolled 94 children with 253 VCZ concentrations. The genotyping of CYP2C19 was performed by polymerase chain reaction (PCR)-pyrosequencing. VCZ trough concentration (C_trough) was detected by high-performance liquid chromatography-tandem mass spectrometry. SPSS 23.0 was used to analyze the correlations between VCZ concentration, CYP2C19 phenotype, adverse effects (AEs), and drug-drug interactions.

RESULTS

A total of 94 children aged between 1 and 18 years (median age 6 years) were enrolled in the study. In total, 42.6% of patients reached the therapeutic range at initial dosing, while the remaining patients reached the therapeutic range after the adjustment of the dose or dosing interval. CYP2C19 gene polymorphism was performed in 59 patients. Among these patients, 24 (40.7%) had the normal metabolizer (NM) phenotype, 26 (44.1%) had the intermediate metabolizer (IM) phenotype, and 9 (15.3%) had the poor metabolizer (PM) phenotype. No cases of the rapid metabolizer (RM) or ultrarapid metabolizer (UM) phenotypes were found. The initial VCZ C_trough was significantly higher in patients with the PM and IM phenotypes than in those with the NM phenotype. The combination of immunosuppressive drugs (ISDs) did not affect VCZ C_trough. The incidence of AEs was 25.5%, and liver function damage (46.2%) and gastrointestinal reactions (19.2%) were the most common.

CONCLUSIONS

Our study showed significant individual differences of VCZ metabolism in children. Combining TDM with CYP2C19 gene polymorphism has important guiding significance for individualized antifungal therapy in pediatric patients.

Ultra-sensitive detection of hydrogen peroxide and levofloxacin using a dual-functional fluorescent probe

Herein, a flower-shaped fluorescent probe was proposed for hydrogen peroxide (H₂O₂) and levofloxacin (LVF) sensing based on MoOx QDs@Co/Zn-MOFs with porous structure. Both MoOx QDs and Co/Zn-MOFs exhibited peroxidase-like properties, and the combination of them greatly aroused the synergistic catalytic capabilities between them. In o-Phenylenediamine (OPD)-H₂O₂ system, MoOx QDs@Co/Zn-MOFs efficiently catalyzed H₂O₂ to produce •OH and then oxidized OPD to its oxidation product (OxOPD). The OxOPD could not only emit blue fluorescence, but also inhibit the fluorescent intensity of MoOx QDs through fluorescence resonance energy transfer (FRET). Moreover, when introducing LVF into the system, the fluorescent intensities of MoOx QDs increased along with the aggregation of themselves while that of OxOPD remained unchanged, which was explained by the joint behavior of FRET and photo-induced electron transfer (PET) instead of the conventional aggregation-induced emission enhancement (AIEE). With these observation, the proposed probe was employed for H₂O₂ and LVF determination in biological samples with the limit of detection (LOD) of 32.60 pmol/L and 0.85 μmol/L, respectively, suggesting the method holds great promises for trace H₂O₂ and LVF monitoring in eco-environment.

Comprehensive Review on Different Analytical Techniques for HIV 1- Integrase Inhibitors: Raltegravir, Dolutegravir, Elvitegravir and Bictegravir

The advent of HIV-Integrase inhibitors (IN) has marked a significant impact on the lives of HIV patients. Since the launch of the first anti retro-viral drug "Azidothymidine" to the recent advances of IN inhibitors, about 27.4 million people benefit by antiretroviral therapy (ART). The path had been challenging due to many crossroads, leading to the discovery of newer targets. One such recent ART target is Integrase. Use of Integrase inhibitors has surpassed the usage of all other ART owing to a strong barrier to resistance and have been reported to be the first-line therapy. Raltegravir, Elvitegravir, Dolutegravir and Bictegravir are US FDA approved IN inhibitors. The high usage of ART created an opportunity to study various analytical techniques for IN inhibitors. Hitherto, no review encompassing all IN inhibitors is presented. Herein, this review describes the analytical techniques employed for IN inhibitors estimation and quantification reported in the literature and official compendia. Literature suggests that most studies focus on LC-MS/MS and HPLC methods for drug estimation, and few reports suggest spectrophotometric, spectrofluorimetric and electrochemical methods. Furthermore, the review presents the techniques that describe the quantification of integrase drugs in various matrices. Although, antiretroviral drugs are extensively used but data suggests that limited studies have been conducted for determination of impurity profile and stability. This therefore, presents a scope to detect and validate impurities in order to meet ICH guidelines for their limits and further to improve the quality and safety of antiretroviral drugs.

Impact on Antibiotic Resistance, Therapeutic Success, and Control of Side Effects in Therapeutic Drug Monitoring (TDM) of Daptomycin: A Scoping Review

Antimicrobial resistance (AR) is a problem that threatens the search for adequate safe and effective antibiotic therapy against multi-resistant bacteria like methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococci (VRE) and Clostridium difficile, among others. Daptomycin is the treatment of choice for some infections caused by Gram-positive bacteria, indicated most of the time in patients with special clinical conditions where its high pharmacokinetic variability (PK) does not allow adequate plasma concentrations to be reached. The objective of this review is to describe the data available about the type of therapeutic drug monitoring (TDM) method used and described so far in hospitalized patients with daptomycin and to describe its impact on therapeutic success, suppression of bacterial resistance, and control of side effects. The need to create worldwide strategies for the appropriate use of antibiotics is clear, and one of these is the performance of therapeutic drug monitoring (TDM). TDM helps to achieve a dose adjustment and obtain a favorable clinical outcome for patients by measuring plasma concentrations of an administered drug, making a rational interpretation guided by a predefined concentration range, and, thus, adjusting dosages individually.

Optimization of voriconazole therapy for treatment of invasive aspergillosis: Pharmacogenomics and inflammatory status need to be evaluated

AIMS

Cytochrome 2C19 genotype-directed dosing of voriconazole (VRC) reduces the incidence of insufficient VRC trough concentrations (C_min ) but does not account for CYP3A polymorphisms, also involved in VRC metabolism. This prospective observational study aimed to evaluate the utility of a genetic score combining CYP2C19 and CYP3A genotypes to predict insufficient initial VRC C_min (<1 mg/L).

METHODS

The genetic score was determined in hematological patients treated with VRC. The higher the genetic score, the faster the metabolism of the patient. The impact of the genetic score was evaluated considering initial VRC C_min and all VRC C_min (n = 159) determined during longitudinal therapeutic drug monitoring.

RESULTS

Forty-three patients were included, of whom 41 received VRC for curative indication. Thirty-six patients had a genetic score ≥2, of whom 11 had an initial insufficient VRC C_min . A genetic score ≥2 had a positive predictive value of 0.31 for having an initial insufficient VRC C_min and initial VRC C_min was not associated with the genetic score. The lack of association between the genetic score and VRC C_min may be related to the inflammatory status of the patients (C-reactive protein [CRP] levels: median [Q1-Q3]: 43.0 [11.0-110.0] mg/L), as multivariate analysis performed on all VRC C_min identified CRP as an independent determinant of the VRC C_min adjusted for dose (P < .0001).

CONCLUSION

The combined genetic score did not predict low VRC exposure in patients with inflammation, which is frequent in patients with invasive fungal infections. Strategies for the individualization of VRC dose should integrate the inflammatory status of patients in addition to pharmacogenetic variants.

LC-MS/MS method for nine different antibiotics

BACKGROUND AND AIMS

TDM of antibiotics can bring benefits to patients and healthcare systems by providing better treatment and saving healthcare resources. We aimed to develop a multi-analyte method for several diverse antibiotics using LC-MS/MS.

MATERIALS AND METHODS

Sample preparation consisted of protein precipitation with methanol, dilution and online extraction using a Turboflow Cyclone column. Separation was performed on a Synergi 4 µm Max RP column and deuterated forms of three antibiotics were used as internal standards.

RESULTS

We present a LC-MS/MS method for the quantitative determination of nine antibiotics, including five cephalosporins, the carbapenem ertapenem, the fluoroquinolone ciprofloxacin as well as the combination drug trimethoprim-sulfamethoxazole from plasma. Additionally, unbound ertapenem and cefazolin were analyzed in plasma water after ultrafiltration using plasma calibrators. Results from routine TDM show the applicability of the method.

CONCLUSION

The presented method is precise and accurate and was introduced in a university hospital, permitting fast TDM of all nine analytes. It was also used in a clinical study for measuring cefazolin free and total concentrations.

Tablets or oral suspension for posaconazole in lung transplant recipients? Consequences for trough concentrations of tacrolimus and everolimus

AIMS

A new formulation of posaconazole (PCZ), delayed-release tablets (PCZ-tab), increases PCZ bioavailability and plasma trough concentrations (C_min ) over those achieved with an oral suspension (PCZ-susp). PCZ is an inhibitor of cytochrome P450 3A4 and P-glycoprotein. We therefore investigated the impact of PCZ-tab treatment on blood C_min and doses of tacrolimus (TAC) and everolimus (EVR).

METHODS

Eighteen lung transplant patients receiving TAC (n = 13) or TAC + EVR (n = 5) between June 2015 and March 2016 were retrospectively included. Ten of these patients received both PCZ-tab and PCZ-susp (i.e. switched patients); the other 8 received only PCZ-tab. Plasma C_min of PCZ (n = 64), blood C_min of TAC (n = 299) and EVR (n = 80) were determined during routine therapeutic drug monitoring by liquid chromatography-tandem mass spectrometry.

RESULTS

PCZ C_min on PCZ-tab treatment (n = 48) was 2.5 times higher than that on PCZ-susp therapy (n = 16), for both PCZ patients (P < .0001) and for switched patients (P = .003). PCZ initiation, regardless of galenic form, increased TAC and EVR C_min adjusted for dose (D), 3-fold and 3.5-fold, respectively (P < .0001 for both). PCZ-tab treatment was associated with a higher TAC C_min /D (PCZ-tab vs PCZ-susp: 0.004 ± 0.004 L^-1 vs 0.009 ± 0.006 L^-1 , P < .0001) and lower TAC daily dose than PCZ-susp (PCZ-tab vs PCZ-susp: 1.08 ± 0.92 vs 2.32 ± 1.62 mg d^-1 , P < .0001). EVR C_min /D was higher and EVR dose tended to be lower on PCZ-tab than on PCZ-susp.

CONCLUSION

The greater PCZ exposure achieved during PCZ-tab treatment increased drug-drug interactions with TAC and EVR, resulting in greater exposure, potentially exposing patients to higher risks of adverse effects.

Development and validation of a UPLC-MS/MS method for simultaneous quantification of levofloxacin, ciprofloxacin, moxifloxacin and rifampicin in human plasma: Application to the therapeutic drug monitoring in osteoarticular infections

BACKGROUND

Fluoroquinolones and rifampicin are antibiotics frequently used for the treatment of osteoarticular infections, and their therapeutic drug monitoring is recommended. The aim of this study was to develop and validate a rapid and selective method of simultaneous quantification of levofloxacin, ciprofloxacin, moxifloxacin and rifampicin with short pretreatment and run times in order to be easily used in clinical practice.

METHODS

After a simple protein precipitation of plasma samples, the chromatographic separation was performed using an ultra-performance liquid chromatography system coupled with mass tandem spectrometry in a positive ionization mode. The mobile phase consisted of a gradient elution of water-formic acid (100:0.1, v/v)-ammonium acetate 2 mM (A) and methanol-formic acid (100:0.1, v/v)-ammonium acetate 2 mM (B) at a flow rate at 0.3 mL/min.

RESULTS

Analysis time was 5 min per run, and all analytes and internal standards eluted within 0.85-1.69 minutes. The calibration curves were linear over the range from 0.5-30 μg/mL for levofloxacin, ciprofloxacin, moxifloxacin and rifampicin with linear regression coefficients above 0.995 for all analytes. The intra-day and inter-day coefficients of variation were below 10 % for lower and higher concentration. This method was successfully applied to drug monitoring in patients with an osteoarticular infection.

CONCLUSION

A simple, rapid, and selective liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of levofloxacin, ciprofloxacin, moxifloxacin and rifampicin in human plasma.

Variability of voriconazole concentrations in patients with hematopoietic stem cell transplantation and hematological malignancies: influence of loading dose, procalcitonin, and pregnane X receptor polymorphisms

AIMS

Voriconazole (VCZ) displays highly variable pharmacokinetics affecting treatment efficacy and safety. We aimed to identify the factors affecting VCZ steady-state trough concentration (Cssmin) to provide evidence for optimizing VCZ treatment regimens.

METHODS

A total of 510 Cssmin of 172 patients with hematopoietic stem cell transplantation and hematologic malignancies and their clinical characteristics and genotypes of FMO, POR, and PXR were included in this study.

RESULTS

In univariate analysis, the standard loading dose of VCZ significantly increased the Cssmin of VCZ (P < 0.001). The Cssmin of VCZ was significantly correlated with patients' total bilirubin (TB) (P < 0.001) and procalcitonin (PCT) (P < 0.001). FMO3 rs2266780 (P = 0.025), POR rs10954732 (P = 0.015), PXR rs2461817 (P = 0.010), PXR rs7643645 (P = 0.003), PXR rs3732359 (P = 0.014), PXR rs3814057 (P = 0.005), and PXR rs6785049 (P = 0.013) have a significant effect on Cssmin of VCZ. Loading dose, TB, PCT level, and PXRrs3814057 polymorphism were independent influencing factors of VCZ Cssmin in the analysis of multivariate linear regression. And loading dose, PCT, and PXR rs3814057 had significant effects on the probability of the therapeutic window of VCZ.

CONCLUSION

The high variability of VCZ Cssmin may be partially explained by loading dose, liver function, inflammation, and PXR polymorphisms. This study suggests the VCZ standard loading dose regimen significantly increased Cssmin and probability of the therapeutic window providing treatment benefits. Patients in the high PCT group may be more likely to exceed 5.5 μg/mL, thus suffering from VCZ toxicity.

Interlaboratory Analysis of Isavuconazole Plasma Concentration Assays Among European Laboratories

BACKGROUND

Under certain circumstances, clinicians treating patients with isavuconazole for invasive aspergillosis or mucormycosis may use therapeutic drug monitoring. However, the accuracy and reproducibility of the various assays used by different laboratories for the quantification of isavuconazole plasma concentrations have yet to be determined.

METHODS

Human plasma samples spiked with known concentrations of isavuconazole were provided to 27 European laboratories that took part in a "round-robin" test (an interlaboratory test performed independently at least 2 times; 2 rounds performed in the current study). Assay methods included liquid chromatography-tandem mass spectrometry (LC-MS/MS), LC with ultraviolet detection (LC-UV), LC with fluorescence detection (LC-FL), and bioassay. The accuracy and reproducibility compared with the known concentrations for each sample in each round were compared overall, between assays, and between laboratories.

RESULTS

Twenty-seven laboratories participated in the study (LC-MS/MS, n = 15; LC-UV; n = 9; LC-FL, n = 1; bioassay, n = 2). In round 1, for nominal concentrations of 1000, 1700, 2500, and 4000 ng/mL, the mean (SD) determined concentrations were 1007 (183), 1710 (323), 2528 (540), and 3898 (842) ng/mL, respectively. In round 2, for nominal concentrations of 1200, 1800, 2400, and 4000 ng/mL, the mean (SD) determined concentrations were 1411 (303), 2111 (409), 2789 (511), and 4723 (798) ng/mL, respectively. Over both rounds, determined concentrations were consistently within 15% of the nominal concentrations for 10 laboratories (LC-MS/MS, n = 4; LC-UV, n = 5; bioassay, n = 1) and consistently exceeded the upper 15% margin for 7 laboratories (LC-MS/MS and LC-UV, n = 3 each; LC-FL, n = 1).

CONCLUSIONS

Alignment of methodologies among laboratories may be warranted to improve the accuracy and reproducibility of therapeutic drug measurements.

Treatment by Posaconazole Tablets, Compared to Posaconazole Suspension, Does Not Reduce Variability of Posaconazole Trough Concentrations

The delayed-release tablet formulation of posaconazole (POS-tab) results in higher plasma POS trough concentrations (C_min) than the oral suspension (POS-susp), which raises the question of the utility of therapeutic drug monitoring (TDM). We aimed to compare the variability of the POS C_min for the two formulations and identify determinants of the POS-tab C_min and its variability. Demographic, biological, and clinical data from 77 allogeneic hematopoietic stem cell transplant patients (874 C_min) treated with POS-tab (n = 41), POS-susp (n = 29), or both (n = 7) from January 2015 to December 2016 were collected retrospectively. Interpatient and within-subject coefficients of variation (CVs) of the C_min adjusted to dose (D) were calculated for each formulation. Between-group comparisons were performed using a linear mixed effects model. The POS C_min was higher for the tablet than for the suspension (median [25th-75th percentile]: 1.8 [1.2-2.4] mg/liter versus 1.2 [0.7-1.6] mg/liter, P < 0.0001). Interpatient CVs for the tablet and suspension were 60.8 versus 63.5% (P = 0.7), whereas within-subject CVs were 39.7 and 44.9%, respectively (P = 0.3). Univariate analysis showed that age and treatment by POS-tab were significantly and positively associated with the POS C_min, whereas diarrhea was associated with a diminished POS C_min Multivariate analysis identified treatment with POS-tab and diarrhea as independent factors of the POS C_min, with a trend toward a lower impact of diarrhea during treatment with POS-tab (P = 0.07). Despite increased POS exposure with the tablet formulation, the variability of the POS C_min was not significantly lower than that of the suspension. This suggests that TDM may still be useful to optimize tablet POS therapy.

Refining the therapeutic range of posaconazole and isavuconazole for efficient therapeutic drug monitoring using a bioassay approach

Therapeutic drug monitoring (TDM) of antifungal triazole was recommended, except for isavuconazole (ISA) whose target trough concentrations (C_min ) need to be specified. Concerning posaconazole (POS), tablet formulation results in higher exposure but no upper C_min threshold has been yet proposed. We aimed to investigate the pharmacokinetic-pharmacodynamic relationship of POS and ISA, using a bioassay approach as surrogate marker of antifungal activity, in order to refine the therapeutic C_min of both antifungals. A bioassay using a cellulose disk diffusion method was performed to determine the growth inhibition zone (GIZ) of POS and ISA on Aspergillus fumigatus and Candida parapsilosis (ISA only). GIZs of plasma from patients undergoing TDM for POS (n = 136) or ISA (n = 40) were determined. GIZs of plasma patients and antifungal C_min were highly correlated for ISA (A. fumigatus: ρ = 0.942, P < 0.0001; C. parapsilosis: ρ = 0.949, P < 0.0001) and POS (ρ = 0.922, P < 0.0001), and these relationships were represented with a Michaelis-Menten model. Based on this modeling, the recommended thresholds of 0.7, 1, and 1.25 mg/L for the POS C_min corresponded to 50.1, 55.2, and 59.1% of the maximal GIZ, respectively. We propose an upper threshold of 4.8 mg/L for the POS C_min and a lower threshold of 2.0 mg/L for the C_min of ISA, as they respectively corresponded to concentrations leading to 90% and 50% of the maximal GIZ on A. fumigatus. The determination of antifungal activity using this bioassay allowed refining target C_min of POS and ISA, especially the upper threshold of POS (4.8 mg/L) and the lower threshold of ISA (2.0 mg/L).

Simple LC-MS/MS Methods Using Core-Shell Octadecylsilyl Microparticulate for the Quantitation of Total and Free Daptomycin in Human Plasma

BACKGROUND

Daptomycin, a cyclic lipopeptide antibiotic, displays high plasma protein binding. This study developed the simple method of liquid chromatographic separation using a core-shell octadecylsilyl microparticulate coupled to tandem mass spectrometry for the quantitation of total and free daptomycin in human plasma.

METHODS

Free daptomycin in plasma was obtained by centrifugal ultrafiltration. Deproteinized plasma specimens were directly separated using a core-shell octadecylsilyl microparticulate with isocratic elution. The mass spectrometer was run in positive-ion electrospray ionization mode. This method was applied to the quantitation of plasma samples in patients treated with intravenous daptomycin.

RESULTS

Daptomycin and diazepam as an internal standard were eluted with a total run time of 10 minutes. The calibration curves of total and free daptomycin in human plasma were linear over the concentration ranges of 1-100 and 0.1-10 mcg/mL, respectively. The lower limits of quantitation of the total and free daptomycin in human plasma were 1.0 and 0.1 mcg/mL, respectively. Their extraction recovery rates in nonfiltrated and ultrafiltrated plasma samples were 106.1% and 98.2%, respectively. Total and free daptomycin did not exhibit any matrix effects in human plasma. The intraday and interday accuracies and imprecisions of total daptomycin were 88.7%-106.0% and 98.7%-105.9%, and within 4.1% and 10.4%, whereas those of free daptomycin were 86.8%-101.6% and 103.0%-107.8%, and within 14.6% and 14.6%, respectively. The plasma concentration ranges of total and free daptomycin in 15 infected patients were 3.01-34.1 and 0.39-3.64 mcg/mL, respectively. The plasma protein binding rate of daptomycin ranged from 80.8% to 94.9%.

CONCLUSIONS

The present simple method with an acceptable analytical performance can be helpful for monitoring the pharmacokinetics of daptomycin in infected patients observed in clinical settings.

Advances in antifungal drug measurement by liquid chromatography-mass spectrometry

Fungal infections, especially invasive types, have become a serious healthcare problem as the immunocompromised population increases. There are five main classes of antifungal drugs: polyenes, flucytosine, allylamines, azoles, and echinocandins. Therapeutic drug monitoring (TDM) is justified for flucytosine and triazoles due to their large inter- and intra-individual pharmacokinetic variability and their high tendency for drug-drug interactions. Available methods for measuring these drugs include bioassay, liquid chromatography and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The LC-MS/MS approach is preferred due to its superior analytic sensitivity and specificity. In this review, we highlight TDM methods by LC-MS/MS for these antifungal drugs searchable in PubMed by December 1, 2018. LC-MS/MS methods that were developed for other purposes such as pharmacokinetics or toxicokinetics were also included. We have critically analyzed these methods with an emphasis on sensitivity, specificity, simplicity, throughput and robustness.

Microextraction by Packed Molecularly Imprinted Polymer Combined Ultra-High-Performance Liquid Chromatography for the Determination of Levofloxacin in Human Plasma

Fluoroquinolones are considered as gold standard for the prevention of bacterial infections. To improve assessment of antibacterial efficacy, a novel method for determination of levofloxacin was developed and validated. Deep eutectic solvents (DESs) as only green solvent were used as a porogen for preparation of water-compatible molecularly imprinted polymers (MIPs) with a pseudotemplate. The DESs-MIPs were characterized in detail, including scanning electron microscope, nitrogen sorption porosimetry, and Fourier transform-infrared spectra. Clearly, the maximum binding capacity of levofloxacin on DESs-MIPs in water and methanol was 0.216 and 0.077 μmol g−1, respectively. The DESs-MIPs as adsorbing materials were applied in microextraction by packed sorbent (MEPS), and the DESs-MIPs-MEPS conditions were optimized. The DESs-MIPs-MEPS coupled with ultra-high-performance liquid chromatography (UHPLC) was used to determine levofloxacin in human plasma. The method was found linear over 0.05–10 μg mL−1 with coefficient of correlation equal to 0.9988. The limit of detection and limit of quantification were 0.012 and 0.04 μg mL−1, respectively. At three spiked levels, the precision of proposed method was between 95.3% and 99.7% with intraday and interday relative standard deviations ≤8.9%. Finally, the developed method was used to examine levofloxacin from human plasma of 20 hospitalized patients after transrectal ultrasound-guided prostate biopsy, and the average concentration (±SD) of levofloxacin was 2.35 ± 0.99 μg mL−1 in plasma.

UPLC-MS/MS method for the simultaneous determination of imatinib, voriconazole and their metabolites concentrations in rat plasma

In the present study, a simple ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method used to measure the plasma concentrations of imatinib, voriconazole and their metabolites (N-desmethyl imatinib and N-oxide voriconazole) in rats simultaneously making use of diazepam as the internal standard (IS) had been developed and validated. A simple protein precipitation by acetonitrile was employed for the sample preparation, then the analytes (imatinib, voriconazole and their metabolites) were eluted on an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using the mobile phase that made up by acetonitrile (A) and 0.1% formic acid in water (B). In positive ion mode, four analytes and IS were monitored by multiple reaction monitoring (MRM) as the following mass transition pairs: m/z 494.3→394.2 for imatinib, m/z 480.3→394.2 for N-desmethyl imatinib, m/z 350.1→281.1 for voriconazole, m/z 366.1→224.1 for N-oxide voriconazole, and m/z 285.0→154.0 for IS. This method exhibited a good linearity for each analyte. Inter-day and intra-day precision were determined with values of 0.3-14.8% and 2.6-14.8%, respectively; the accuracy values were from -12.5% to 10.2%. Finally, data of matrix effect, extraction recovery, and stability were all conformed to the bioanalytical method validation of acceptance criteria of FDA recommendations. This method is an efficient tool for simultaneous determination of the four analytes and has been successfully applied for pharmacokinetic study in rats.

Development and validation of a volumetric absorptive microsampling assay for analysis of voriconazole and voriconazole N-oxide in human whole blood

Voriconazole is a broad-spectrum antifungal triazole drug for the treatment of invasive fungal infections. It is extensively metabolized by hepatic drug metabolizing enzymes cytochrome (CYP) 2C19 and CYP3A4. Selective inhibition of intestinal CYP3A4 by grapefruit juice may increase the oral bioavailability of voriconazole in children. To test this hypothesis it is necessary to develop a sensitive assay for measuring voriconazole and its major metabolites in a small volume of blood. Mitra® devices from Neoteryx were employed to develop and validate the assay for the quantitation of voriconazole and voriconazole N-oxide. Mitra® devices utilize volumetric absorptive microsampling (VAMS™) technology that enables accurate and precise collection of a fixed volume (10 μL of blood), reducing or eliminating the volumetric blood hematocrit assay-bias associated with the dried blood spotting technique. We developed an ultra-performance liquid chromatographic method with tandem mass spectrometry detection for quantification of voriconazole and voriconazole N-oxide. Sample extraction of Mitra® devices, followed by reversed-phase chromatographic separation and selective detection using tandem mass spectrometry with a 4.00 minute runtime per sample was employed. Standard curves were linear between 10.0 to 10,000 ng/mL for both voriconazole and voriconazole N-oxide. Intra- and inter-day accuracy were within 87-102% and precision (CV) was <12% based on a 3-day validation study. Recoveries were ≥94 % for voriconazole and ≥87 % for voriconazole N-oxide. Voriconazole and voriconazole N-oxide were stable in human whole blood under assay conditions (19 h at room temperature and 24 h in autosampler). Voriconazole was stable for 1-month in dried microsamples under different conditions (4, -20 and -78 °C). This assay provides an efficient quantitation of voriconazole and voriconazole N-oxide and is ready to be implemented for the analysis of whole blood microsamples in a pediatric clinical trial investigating the impact of intestinal inhibition of CYP3A4 on voriconazole pharmacokinetics.

Inflammation is a potential risk factor of voriconazole overdose in hematological patients

Voriconazole (VRC) overdoses are frequent and expose patients at high risk of adverse effects. This case-control study performed in hematological patients who benefited from VRC therapeutic drug monitoring from January 2012 to December 2015 aimed to identify risk factors of VRC overdose. Pharmacogenetic, biological, and demographic parameters at the time of VRC trough concentration (C_min ) were retrospectively collected from medical records. Cases (VRC overdose: defined by a VRC C_min ≥ 4 mg/L; n = 31) were compared to controls (no VRC overdose: defined by VRC C_min < 4 mg/L; n = 31) using nonparametric or chi-square tests followed by multivariable analysis. VRC overdoses were significantly associated with high CRP and bilirubin levels, intravenous administration, and age in univariable analysis. In contrast, the proportion of CYP genotypes (CYP2C19, CYP3A4, or CYP3A5, considered alone or combined in a combined genetic score) were not significantly different between patients who experienced a VRC overdose and those who did not. In multivariable analysis, the class of CRP level (defined by median CRP levels of 96 mg/L) was the sole independent risk factor of VRC overdose (P < 0.01). Patients with CRP levels > 96 mg/L) had a 27-fold (IC 95%: [6-106]) higher risk of VRC overdose than patients with CRP levels ≤ 96 mg/L. This study demonstrates that inflammatory status, assessed by CRP levels, is the main risk factor of VRC overdose in French hematological patients, whereas pharmacogenetic determinants do not appear to be involved.

Integrating anatomo-physiological changes and pharmacogenomics in anti-infective therapy management: is it a major concern?

Success of anti-infective therapy is a major challenge in some patients given anatomo-physiological changes and genetic variations. In this case anecdote, we report the management strategy of a patient suffering from chronic pulmonary aspergillosis in a context of anorexia nervosa and genetic polymorphism.

Separation and Identification of Isomeric and Structurally Related Synthetic Cannabinoids Using 2D Liquid Chromatography and High Resolution Mass Spectrometry

Novel psychoactive substances (NPS) are emerging drugs of abuse that are variations of existing compounds intended to cause a CNS psychotropic effect. Some NPS are so comparable in structure and physicochemical properties that they co-elute using traditional single column chromatographic techniques and therefore will not be detected as individual compounds. 2D liquid chromatography (2D-LC) has demonstrated applicability in difficult separations of small molecules and compounds in complex mixtures. It was hypothesized that this technique could also be used to separate co-eluting isomeric and structurally related, non-isomeric NPS, including synthetic cannabinoids (SC). Initial studies assessed several parameters, including column type, mobile phase, analysis time, gradient and flow rate, to optimize a 2D-LC method for separation and analysis of SC. The final comprehensive on-line 2D-LC method employed a Bonus-RP column in the first dimension (1D) coupled with UV detection and a biphenyl column in the second dimension (2D) coupled with QTOF-MS detection in full scan positive mode. To test the utility of the method, three SC mixes were created, each containing five compounds that were unresolvable in a traditional, 1D-LC separation; one mix with isomeric compounds and two with structurally related but non-isomeric compounds. Contour plots of UV absorbance in 1D and MS ion intensity in 2D demonstrated that all components in each mixture were successfully resolved using the 2D-LC separation method. This research serves as proof-of-concept for the application of 2D-LC to the separation of isomeric and structurally related SC. With further optimization and validation, 2D-LC may be a generally useful tool for separation of complex mixtures of NPS.

Analysis of imidazoles and triazoles in biological samples after MicroExtraction by packed sorbent

This paper reports the MEPS-HPLC-DAD method for the simultaneous determination of 12 azole drugs (bifonazole, butoconazole, clotrimazole, econazole, itraconazole, ketoconazole, miconazole, posaconazole, ravuconazole, terconazole, tioconazole and voriconazole) administered to treat different systemic and topical fungal infections, in biological samples. Azole drugs separation was performed in 36 min. The analytical method was validated in the ranges as follows: 0.02–5 μg mL⁻¹ for ravuconazole; 0.2–5 μg mL⁻¹ for terconazole; 0.05–5 μg mL⁻¹ for the other compounds. Human plasma and urine were used as biological samples during the analysis, while benzyl-4-hydroxybenzoate was used as an internal standard. The precision (RSD%) and trueness (Bias%) values fulfill with International Guidelines requirements. To the best of our knowledge, this is the first HPLC-DAD procedure coupled to MEPS, which provides the simultaneous analysis of 12 azole drugs, available in the market, in human plasma and urine. Moreover, the method was successfully applied for the quantitative determination of two model drugs (itraconazole and miconazole) after oral administration in real samples.

Development of a liquid chromatography tandem mass spectrometry method for the simultaneous measurement of voriconazole, posaconazole and itraconazole

Background Azole-based antifungals are the first-line therapy for some of the most common mycoses and are now also being used prophylactically to protect immunocompromised patients. However, due to variability in both their metabolism and bioavailability, therapeutic drug monitoring is essential to avoid toxicity but still gain maximum efficacy. Methods Following protein precipitation of serum with acetonitrile, 20  µL of extract was injected onto a 2.1 × 50 mm Waters Atlantis dC18 3  µm column. Detection was via a Waters Quattro Premier XE tandem mass spectrometer operating in ESI-positive mode. Multiple reaction monitoring (MRM) detected two product ions for each compound and one for each isotopically labelled internal standard. Ion suppression, linearity, stability, matrix effects, recovery, imprecision, lower limits of measuring interval and detection were all assessed. Results Optimal chromatographic separation was achieved using gradient elution over 8 minutes. Voriconazole, posaconazole and itraconazole eluted at 1.71, 2.73 and 3.41 min, respectively. The lower limits of measuring interval for all three compounds was 0.1 mg/L. The assay was linear to 10 mg/L for voriconazole (R²= 0.995) and 5 mg/L for posaconazole (R²= 0.990) and itraconazole (R²= 0.991). The assay was both highly accurate and precise with % bias of voriconazole, posaconazole and itraconazole, respectively, when compared with previous NEQAS samples. The intra-assay precision (CV%) was 1.6%, 2.5% and 1.9% for voriconazole, posaconazole and itraconazole, respectively, across the linear range. Conclusion A simple and robust method has been validated for azole antifungal therapeutic drug monitoring. This new assay will result in a greatly improved sample turnaround time and will therefore vastly increase the clinical utility of azole antifungal drug monitoring.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Successful Treatment of a Pacemaker Infection with Intraperitoneal Daptomycin

We investigated the pharmacokinetics of intraperitoneal administration of daptomcyin in a peritoneal dialysis (PD) patient treated for a pacemaker infection with Staphylococcus epidermidis. After initial start of intravenous daptomycin at 9 mg/kg body weight every 48 hours, the therapy was switched to intraperitoneal administration of 5.3 mg/kg body weight in 1 L icodextrin 7.5% with a dwell time of 12 hours overnight every 48 hours. Therapeutic drug monitoring (TDM) was performed at 4 hours and 24 hours after dose administration. Due to high peak concentration above target peak concentration, the dose was reduced to a final maintenance dose of 3.2 mg/kg body weight. Data from this single case suggest that serum drug concentration above the minimal inhibitory concentration (MIC) can be easily achieved with intraperitoneal administration of daptomycin every 48 hours even with a lower dose, as recommended for the intravenous administration, but measurement of serum concentration and dose adjustments are mandatory in such cases.

Advances in Clinical Mass Spectrometry

Although mass spectrometry has been used clinically for decades, the advent of immunoassay technology moved the clinical laboratory to more labor saving automated platforms requiring little if any sample preparation. It became clear, however, that immunoassays lacked sufficient sensitivity and specificity necessary for measurement of certain analytes or for measurement of analytes in specific patient populations. This limitation prompted clinical laboratories to revisit mass spectrometry which could additionally be used to develop assays for which there was no commercial source. In this chapter, the clinical applications of mass spectrometry in therapeutic drug monitoring, toxicology, and steroid hormone analysis will be reviewed. Technologic advances and new clinical applications will also be discussed.

Development and Validation of Voriconazole Concentration by LC-MS-MS: Applied in Clinical Implementation

BACKGROUND

Voriconazole (VRZ) is a triazole antifungal used for treatment of invasive fungal infection, which is a life-threatening condition. Therapeutic drug monitoring is recommended for identifying the optimal dose in patients who have hepatic/renal impairment or reduced function of the CYP2C19 metabolizing enzyme.

METHODS

One hundred microliters of sample plasma was extracted by protein precipitated with 200 μl of acetonitrile containing fluconazole as internal standard (IS). After vortexing and centrifugation, supernatant was dried and reconstituted with 100 μl of mobile phase (ACN: 0.1% formic acid in 10 mM Ammonium acetate) (50:50 v/v) before injected. The column was C18, 2.7 μm, 3.0 × 50 mm at flow rate of 0.5 ml/min with retention time of 0.5 and 0.75 min for VRZ and IS, respectively. The tandem mass spectrometer was set in multiple reactions monitoring (MRM) mode with the following transition; VRZ m/z 350.10→281.10 and 307.20→220.20 (IS).

RESULTS

The accuracy and precision inter- and intra-day were less than 9%, over the range 0.05-10 μg/ml. The linearity was consistent (r² = 0.9987) and recovery was more than 85.0% for both analyses.

CONCLUSION

This method is applicable for routine monitoring of patients' VRZ plasma level with fast and accurate runtime to assess CYP2C19 genotype.

Recent developments in the chromatographic bioanalysis of approved kinase inhibitor drugs in oncology

In recent years (2010-present) there has been an increase in the number of publications reporting the development, validation and use of bioanalytical methods in the rapidly expanding drug class of small molecule protein kinase inhibitors. Most reports describe the technological set-up of the methods that have allowed for drug concentration measurements from various sample types. This includes plasma, dried blood-spot, and tissue-analysis. Also method development, exploration of various techniques, as well as measurement and identification of metabolites were addressed. For the bioanalysis, a variety of sample-pretreatment methods like protein-precipitation, liquid-liquid extraction, and solid-phase extraction have been employed, all varying in complexity, cleanliness and time-consumption. Chromatographic separation, nowadays, is more focused on separating components from ion-suppressive effects, since for MS/MS detection, various components do not have to be baseline separated. For detection multiple types of detectors were used, ranging from state-of-the-art high resolution, and tandem mass spectrometry with low picogram per milliliter detection limits to the classical UV-detector with several nanograms per milliliter limits. As new bioanalytical methods have arisen that do rely on chromatographic separation, for example for high-throughput analysis, these are addressed in this review as well.