Population pharmacokinetics of ceftriaxone and pharmacodynamic considerations in haemodialysed patients

Unraveling Ceftriaxone Dosing: Free Drug Prediction, Threshold Optimization, and Model Validation

Ceftriaxone is pivotal in treating severe infections; however, predicting unbound plasma ceftriaxone (CEFu) from total ceftriaxone (CEFtot) remains challenging. This study aimed to (1) predict CEFu from CEFtot, (2) determine optimal target for CEFtot trough concentration in plasma, (3) perform an external validation of published models, and (4) to ascertain whether the CEF dosing regimen was sufficient to achieve the therapeutic objectives. CEFu predictions based on CEFtot were evaluated using previously published models. Optimal CEFtot targets for an MIC of 1mg/L were calculated to achieve CEFu concentrations above MIC and 4xMIC 100% of the time. External validation was conducted assessing serum albumin, CEFtot and CEFu and comparing predicted CEFu across models. Retrospective data, comprising 408 CEFtot from 222 patients, were analyzed to assess the probability of target attainment (PTA) based on model predicted CEFu. CEFu predictions based on CEFtot were evaluated using previously published models. Optimal CEFtot targets for an MIC of 1mg/L were calculated to achieve CEFu concentrations above MIC and 4xMIC 100% of the time. External validation was conducted assessing serum albumin, CEFtot and CEFu and comparing predicted CEFu across models. Retrospective data, comprising 408 CEFtot from 222 patients, were analyzed to assess the probability of target attainment (PTA) based on model predicted CEFu. Optimal CEFtot trough concentration targets ranged from 2.0 mg/L to 16.9 mg/L (1xMIC) and from 7.9 mg/L to 56.2 mg/L (4xMIC) across models. Some models accurately predicted CEFu obtained from prospective external validation. In the retrospective cohort, PTA ranged from 94.4% to 98.7% for 1xMIC and from 66.9% to 97.3% for 4xMIC. Modeling or direct quantification of CEFu may improve patient outcomes, but achieving this requires standardized analytical approaches and further research to assess the ability of published models to accurately predict CEFu.

Unexpected Sudden Deaths Following the Co-administration of Ceftriaxone and Lansoprazole: A Case Series

Ceftriaxone and lansoprazole are commonly used in clinical settings, but recent analyses indicate a potential risk for QTc prolongation and cardiac events when used together. This case series examines three patients from a cohort of sudden death cases at a single institution over a decade, who received both medications within 24 hours before death. Three cases were identified, each with contributing factors for cardiac arrhythmias. The results underscore the importance of monitoring and possibly avoiding this drug combination in patients at risk of QT prolongation, pending further investigation into the underlying mechanisms.

Population pharmacokinetics of antibacterial agents in the older population: a literature review

INTRODUCTION

Older individuals face an elevated risk of developing bacterial infections. The optimal use of antibacterial agents in this population is challenging because of age-related physiological alterations, changes in pharmacokinetics (PK) and pharmacodynamics (PD), and the presence of multiple underlying diseases. Therefore, population pharmacokinetics (PPK) studies are of great importance for optimizing individual treatments and prompt identification of potential risk factors.

AREA COVERED

Our search involved keywords such as 'elderly,' 'old people,' and 'geriatric,' combined with 'population pharmacokinetics' and 'antibacterial agents.' This comprehensive search yielded 11 categories encompassing 28 antibacterial drugs, including vancomycin, ceftriaxone, meropenem, and linezolid. Out of 127 studies identified, 26 (20.5%) were associated with vancomycin, 14 (11%) with meropenem, and 14 (11%) with piperacillin. Other antibacterial agents were administered less frequently.

EXPERT OPINION

PPK studies are invaluable for elucidating the characteristics and relevant factors affecting the PK of antibacterial agents in the older population. Further research is warranted to develop and validate PPK models for antibacterial agents in this vulnerable population.

Ceftriaxone-Induced Encephalopathy in a Patient With End-Stage Renal Disease on Hemodialysis

Ceftriaxone-induced encephalopathy is a rare but known adverse effect secondary to neurotoxicity, especially in patients with end-stage renal disease (ESRD) on hemodialysis. The common presenting symptoms include myoclonus, psychosis, and seizures. We are presenting a case of a 77-year-old female patient who presented with confusion and jerky movements of her lips and extremities. Her initial workup was negative for stroke and seizure disorder. A probable diagnosis of ceftriaxone-induced encephalopathy was made using an Adverse Drug Reaction (ADR) probability scale (Naranjo scale) with a Naranjo score of 5. The patient's symptoms resolved after discontinuation of ceftriaxone. Ceftriaxone is a commonly used intravenous antibiotic in the inpatient setting, and thus clinicians should be aware of this rare adverse reaction in patients with ESRD.

Validating a novel three-times-weekly post-hemodialysis ceftriaxone regimen in infected Indigenous Australian patients-a population pharmacokinetic study

OBJECTIVES

To describe the total and unbound population pharmacokinetics of a 2 g three-times-weekly post-dialysis ceftriaxone regimen in Indigenous Australian patients requiring hemodialysis.

METHODS

A pharmacokinetic study was carried out in the dialysis unit of a remote Australian hospital. Adult Indigenous patients on intermittent hemodialysis (using a high-flux dialyzer) and treated with a 2 g three-times-weekly ceftriaxone regimen were recruited. Plasma samples were serially collected over two dosing intervals and assayed using validated methodology. Population pharmacokinetic analysis and Monte Carlo simulations were performed using Pmetrics in R. The probability of pharmacokinetic/pharmacodynamic target attainment (unbound trough concentrations ≥1 mg/L) and toxicity [trough concentrations (total)  ≥100 mg/L] were simulated for various dosing strategies.

RESULTS

Total and unbound concentrations were measured in 122 plasma samples collected from 16 patients (13 female) with median age 57 years. A two-compartment model including protein-binding adequately described the data, with serum bilirubin concentrations associated (inversely) with ceftriaxone clearance. The 2 g three-times-weekly regimen achieved 98% probability to maintain unbound ceftriaxone concentrations ≥1 mg/L for a serum bilirubin of 5 µmol/L. Incremental accumulation of ceftriaxone was observed in those with bilirubin concentrations >5 µmol/L. Three-times-weekly regimens were less probable to achieve toxic exposures compared with once-daily regimens. Ceftriaxone clearance was increased by >10-fold during dialysis.

CONCLUSIONS

A novel 2 g three-times-weekly post-dialysis ceftriaxone regimen can be recommended for a bacterial infection with an MIC ≤1 mg/L. A 1 g three-times-weekly post-dialysis regimen is recommended for those with serum bilirubin ≥10 µmol/L. Administration of ceftriaxone during dialysis is not recommended.

Analysis of the frequency of ceftriaxone-induced encephalopathy using the Japanese Adverse Drug Event Report database

BACKGROUND

The profile of ceftriaxone-induced encephalopathy is not well understood.

AIM

To identify risk factors associated with ceftriaxone-induced encephalopathy.

METHOD

In this observational study, anonymised patient data were retrieved from the open-access Japanese Adverse Drug Event Report database for ceftriaxone users aged 20 years or higher.

RESULTS

Data of 256,788 individuals and 12,160 cases of encephalopathy were extracted, and 2,939 ceftriaxone users, of whom 193 had encephalopathy, were identified. A disproportionate prevalence of encephalopathy was observed among the ceftriaxone users (reported odds ratio = 1.42; 95% confidence interval [CI] = 1.23-1.65; p < 0.001). Multivariate logistic regression analysis of 2,057 ceftriaxone users showed encephalopathy was associated with female sex (odds ratio [OR] = 1.52; 95% CI, 1.05-2.19; p = 0.027), chronic kidney disease (OR = 2.32; 95% CI, 1.47-3.67; p < 0.001), a ceftriaxone dosage of > 2 g/day (OR = 2.66; 95% CI, 1.66-4.26; p < 0.001), and a treatment duration of > 14 days (OR = 1.94; 95% CI, 1.21-3.11; p = 0.006).

CONCLUSION

Patients with chronic kidney disease, receiving ceftriaxone at a dosage of > 2 g/day, being treated for over 14 days, and/or females may be at an increased risk of ceftriaxone-induced encephalopathy.

Two cases of ceftriaxone-induced encephalopathy treated by hemoperfusion in hemodialysis patients

Ceftriaxone is a third‐generation cephalosporin commonly used to treat infection. However, encephalopathy is an emerging adverse effect of ceftriaxone infusion. These patients present with various symptoms, including those of neurotoxicity, that typically resolve 1 week after discontinuation of ceftriaxone. We experienced two cases of ceftriaxone‐induced encephalopathy that were successfully treated by rapid removal of ceftriaxone by hemoperfusion.

Optimal Dosing of Ceftriaxone in Infants Based on a Developmental Population Pharmacokinetic-Pharmacodynamic Analysis

Ceftriaxone is a third-generation cephalosporin used to treat infants with community-acquired pneumonia. Currently, there is a large variability in the amount of ceftriaxone used for this purpose in this particular age group, and an evidence-based optimal dose is still unavailable. Therefore, we investigated the population pharmacokinetics of ceftriaxone in infants and performed a developmental pharmacokinetic-pharmacodynamic analysis to determine the optimal dose of ceftriaxone for the treatment of infants with community-acquired pneumonia. A prospective, open-label pharmacokinetic study of ceftriaxone was conducted in infants (between 1 month and 2 years of age), adopting an opportunistic sampling strategy to collect blood samples and applying high-performance liquid chromatography to quantify ceftriaxone concentrations. Developmental population pharmacokinetic-pharmacodynamic analysis was conducted using nonlinear mixed effects modeling (NONMEM) software. Sixty-six infants were included, and 169 samples were available for pharmacokinetic analysis. A one-compartment model with first-order elimination matched the data best. Covariate analysis elucidated that age and weight significantly affected ceftriaxone pharmacokinetics. According to the results of a Monte Carlo simulation, with a pharmacokinetic-pharmacodynamic target of a free drug concentration above the MIC during 70% of the dosing interval (70% fT _>MIC), regimens of 20 mg/kg of body weight twice daily for infants under 1 year of age and 30 mg/kg twice daily for those older than 1 year of age were suggested. The population pharmacokinetics of ceftriaxone were established in infants, and evidence-based dosing regimens for community-acquired pneumonia were suggested based on developmental pharmacokinetics-pharmacodynamics.

Pharmacokinetics and Pharmacodynamics of Anti-infective Agents during Continuous Veno-venous Hemofiltration in Critically Ill Patients: Lessons Learned from an Ancillary Study of the IVOIRE Trial

BACKGROUND

Hemofiltration rate, changes in blood and ultrafiltration flow, and discrepancies between the prescribed and administered doses strongly influence pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobial agents during continuous veno-venous hemofiltration (CVVH) in critically ill patients.

METHODS

Ancillary data were from the prospective multicenter IVOIRE (hIgh VOlume in Intensive caRE) study. High volume (HV, 70 mL/kg/h) was at random compared with standard volume (SV, 35 mL/kg/h) CVVH in septic shock patients with acute kidney injury (AKI). PK/PD parameters for all antimicrobial agents used in each patient were studied during five days.

RESULTS

Antimicrobial treatment met efficacy targets for both percentage of time above the minimal inhibitory concentration and inhibitory quotient. A significant correlation was observed between the ultrafiltration flow and total systemic clearance (Spearman test: P < 0.005) and between CVVH clearance and drug elimination half-life (Spearman test: P < 0.005). All agents were easily filtered. Mean sieving coefficient ranged from 38.7% to 96.7%. Mean elimination half-life of all agents was significantly shorter during HV-CVVH (from 1.29 to 28.54 h) than during SV-CVVH (from 1.51 to 33.85 h) (P < 0.05).

CONCLUSIONS

This study confirms that CVVH influences the PK/PD behavior of most antimicrobial agents. Antimicrobial elimination was directly correlated with convection rate. Current antimicrobial dose recommendations will expose patients to underdosing and increase the risk for treatment failure and development of resistance. Dose recommendations are proposed for some major antibiotic and antifungal treatments in patients receiving at least 25 mL/kg/h CVVH.

High-Dose Ceftriaxone for Bacterial Meningitis and Optimization of Administration Scheme Based on Nomogram

High dosages of ceftriaxone are used to treat central nervous system (CNS) infections. Dosage adaptation according to the glomerular filtration rate is currently not recommended. Ceftriaxone pharmacokinetics (PK) was investigated by a population approach in patients enrolled in a French multicenter prospective cohort study who received high-dose ceftriaxone for CNS infection as recommended by French guidelines (75 to 100 mg/kg of body weight/day without an upper limit). Only those with suspected bacterial meningitis were included in the PK analysis. A population model was developed using Pmetrics. Based on this model, a dosing nomogram was developed, using the estimated glomerular filtration rate (eGFR) and total body weight as covariates to determine the optimal dosage allowing achievement of targeted plasma trough concentrations. Efficacy and toxicity endpoints were based on previous reports, as follows: total plasma ceftriaxone concentrations of ≥20 mg/liter in >90% of patients for efficacy and ≤100 mg/liter in >90% of patients for toxicity. Based on 153 included patients, a two-compartment model including eGFR and total body weight as covariates was developed. The median value of the unbound fraction was 7.57%, and the median value of the cerebral spinal fluid (CSF)/plasma ratio was 14.39%. A nomogram was developed according to a twice-daily regimen. High-dose ceftriaxone administration schemes, used to treat meningitis, should be adapted to the eGFR and weight, especially to avoid underdosing using current guidelines. (This study has been registered at ClinicalTrials.gov under identifier NCT01745679.).

Efficacy of Ceftriaxone 1 g daily Versus 2 g daily for The Treatment of Community-Acquired Pneumonia: A Systematic Review with Meta-Analysis

Introduction: Ceftriaxone has been recommended as a first-line treatment for various infections; however, the doses for pneumonia have not been a consensus in randomized clinical trials. To compare ceftriaxone 1 g daily efficacy to other ceftriaxone dosing regimens in community-acquired pneumonia. Area covered: We performed a systematic review and meta-analysis on PubMed, Web of Science, Scopus, and LILACS. Randomized controlled trials of ceftriaxone in community-acquired pneumonia were included. Outcomes included clinical cure in modified intention-to-treatment, clinically and microbiologically evaluable patients. Expert opinion: Ceftriaxone dosages of 1 g daily are as safe and effective as other antibiotic regimens for community-acquired pneumonia. Twenty-four articles fulfilled the inclusion criteria. Twelve studies evaluated ceftriaxone regimens at a dosage of 2 g daily and 12 studies evaluated ceftriaxone at a dosage of 1 g daily. The odds-ratio of clinical cure in the modified intention-to-treatment patients administered either ceftriaxone (4666 patients) or a comparator (4411 patients) was 0.98 (95% CI [0.82-1.17]). Comparator regimens showed similar efficacy to ceftriaxone regimens of 1 g daily, with an odds ratio of 1.03 (95% CI [0.88-1.20]). Dosages higher than ceftriaxone 1 g daily did not result in improved clinical outcomes for community-acquired pneumonia patients (OR 1.02, 95% CI [0.91-1.14]).

Pharmacokinetics of ceftriaxone in patients undergoing continuous renal replacement therapy

BACKGROUND

The duration of time for which the serum levels exceed the minimum inhibitory concentration (MIC) is an important pharmacokinetics (PK)/pharmacodynamics (PD) parameter correlating with efficacy for the antibiotic, ceftriaxone (CTRX). However, no reports exist regarding the PK or PD in patients undergoing continuous renal replacement therapy (CRRT). The purpose of this study was to examine the PK and safety of CTRX in patients undergoing CRRT in order to establish safer and more effective regimens.

METHODS

CTRX (1 g once a day) was intravenously administered four or more times to nine patients undergoing CRRT. Blood was collected after administration to measure CTRX concentrations in serum and the filtration fraction of CRRT by high-performance liquid chromatography. In addition to calculating PK parameters from serum CTRX, we (a) estimated by simulation CTRX concentrations when the dose interval was extended to once every 2 or 3 days, (b) calculated CTRX clearance via CRRT from CTRX concentrations in the filtration fraction, and (c) assessed the safety of CTRX use.

RESULTS

Total body clearance and the half-life of CTRX were 7.46 mL/min (mean) and 26.5 h, respectively, in patients undergoing CRRT. CTRX was found in the filtration fraction, and the estimated clearance by CRRT was about 70% of total body clearance. Simulations revealed that even when the dose interval is increased to 2 or 3 days, CTRX would retain its efficacy.

CONCLUSIONS

Our findings suggest that, depending on the condition of patients undergoing CRRT, CTRX could be used safely against pathogens with a CTRX MIC ≤2 µg/mL, even when extending the dose interval.

How do we use therapeutic drug monitoring to improve outcomes from severe infections in critically ill patients?

High mortality and morbidity rates associated with severe infections in the critically ill continue to be a significant issue for the healthcare system. In view of the diverse and unique pharmacokinetic profile of drugs in this patient population, there is increasing use of therapeutic drug monitoring (TDM) in attempt to optimize the exposure of antibiotics, improve clinical outcome and minimize the emergence of antibiotic resistance. Despite this, a beneficial clinical outcome for TDM of antibiotics has only been demonstrated for aminoglycosides in a general hospital patient population. Clinical outcome studies for other antibiotics remain elusive. Further, there is significant variability among institutions with respect to the practice of TDM including the selection of patients, sampling time for concentration monitoring, methodologies of antibiotic assay, selection of PK/PD targets as well as dose optimisation strategies. The aim of this paper is to review the available evidence relating to practices of antibiotic TDM, and describe how TDM can be applied to potentially improve outcomes from severe infections in the critically ill.

Population pharmacokinetics of ceftriaxone in critically ill septic patients: a reappraisal

AIMS

To investigate the population pharmacokinetics of ceftriaxone in critically ill patients suffering from sepsis, severe sepsis or septic shock.

METHODS

Blood samples were collected at preselected times in 54 adult patients suffering from sepsis, severe sepsis or septic shock in order to determine ceftriaxone concentrations using high-performance liquid chromatography-ultraviolet detection. The pharmacokinetics of ceftriaxone were assessed on two separate occasions for each patient: on the second day of ceftriaxone therapy and 48 h after catecholamine withdrawal in patients with septic shock, or on the fifth day in patients with sepsis. The population pharmacokinetics of ceftriaxone were studied using nonlinear mixed effects modelling.

RESULTS

The population estimates (interindividual variability; coefficient of variation) for ceftriaxone pharmacokinetics were: a clearance of 0.88 l h(-1) (49%), a mean half-life of 9.6 h (range 0.83-28.6 h) and a total volume of distribution of 19.5 l (range 6.48-35.2 l). The total volume of distribution was higher than that generally found in healthy individuals and increased with the severity of sepsis. However, the only covariate influencing the ceftriaxone pharmacokinetics was creatinine clearance. Dosage simulations showed that the risk of ceftriaxone concentrations dropping below the minimum inhibitory concentration threshold was low.

CONCLUSIONS

Despite the wide interpatient variability of ceftriaxone pharmacokinetic parameters, our results revealed that increasing the ceftriaxone dosage when treating critically ill patients is unnecessary. The risk of ceftriaxone concentrations dropping below the minimum inhibitory concentration threshold is limited to patients with high glomerular filtration rates or infections with high minimum inhibitory concentration pathogens (>1 mg l(-1)).

[Questionnaire surveying nephrologists on drug dose adjustment in patients with impaired kidney function]

OBJECTIVE

Our intention was to assess knowledge and requirements related to drug dose adjustment in patients with impaired kidney function.

METHOD

In 2005, we sent a questionnaire containing 22 questions to nephrologists in Germany and Austria. With 77 responses, the study was not representative. However, it was probably of importance for the target group of practising physicians and potential users of a future drug information system.

RESULTS

Only 28% of the responding colleagues use the package inserts; these are obviously not considered to be an obligatory guideline for dose adjustment. The most common dosing problems (p < 0.05) were associated with anti-infective (48%) and anti-cancer drugs (25%). The greatest problems with dosing were encountered within intensive care units (29%). The risk of excessive dosing is estimated significantly more serious than the risk of underdosing (51% vs. 23%, p = 0.02). There was support for the statement that for cephalosporin antibiotics the trough levels are more important than peak levels (58% vs. 27%, p < 0.01). However, only 8% knew that in patients with impaired kidney function, trough concentrations of aminoglycosides and vancomycin need to be higher than in patients with normal kidney function for adequate peak levels to be obtained. Forty-five percent of respondents erroneously presumed that ceftriaxone must be adjusted to the kidney function. Half of the respondents were incorrect in assuming that ceftriaxone or moxifloxacin would be removed by dialysis.

CONCLUSIONS

We see the need for more knowledge-based information on drug dosing in patients with kidney impairment and those in the intensive care unit. The risk to life posed by underdosage might be underestimated, especially for anti-infective drugs.

The pharmacokinetics of ceftriaxone based on population pharmacokinetics and the prediction of efficacy in Japanese adults

OBJECTIVE

By using a population pharmacokinetic analysis method, we predicted the efficacy of Ceftriaxone (CTRX) based on the pharmacokinetics of CTRX in Japanese adults and the sensitivity of infective organisms to CTRX in 2004. In addition, we clarified the difference in efficacy between once-a-day administration and twice-a-day administration.

METHODS

The population pharmacokinetic analysis was based on the serum concentrations of CTRX already published by NONMEM. The possible effect of body weight and age on the pharmacokinetics of CTRX was examined using a model which incorporated the change of a specific protein-binding ratio of CTRX. A Monte Carlo simulation was conducted based on the population pharmacokinetic parameters obtained by this analysis, and thereby the time above MIC (TAM) was determined from the MIC values of CTRX administered once at 0.5, 1, and 2 g and twice at 1 g. The efficacy ratio was predicted from the TAM thus obtained.

RESULTS

Because the time course of serum concentration of CTRX in adult subjects was fitted to a 2-compartment model and both body weight and age were not incorporated as the covariate, the dosing method by which a fixed amount of CTRX is administered to patients has been thought to be adequate. Based on the efficacy ratio estimated from the MIC of CTRX, we have predicted that the once-a-day administration of CTRX even at 0.5g is effective on various infecting organisms.