Reporting Guidelines for Clinical Pharmacokinetic Studies: The ClinPK Statement

Population pharmacokinetics of bedaquiline: a systematic review

BACKGROUND AND OBJECTIVES

Bedaquiline (BDQ) plays a critical role in the treatment of multidrug-resistant tuberculosis (MDR-TB). However, the large pharmacokinetic (PK) variability of BDQ presents a significant challenge in its clinical use. This study aimed to summarize the population PK characteristics of BDQ and to identify significant covariates affecting the PK variation of BDQ.

METHODS

The PubMed and Web of Science databases were systematically searched from their inception to October 1, 2023. Population pharmacokinetics (PPK) studies on BDQ were searched and identified in this review. The PK characteristics of included studies and the significant covariates were systematically summarized.

RESULTS

Eight studies conducted in adults and one in children and adolescents were included in this review. A three disposition compartments with dynamic absorption transport chamber model was the commonly used structural model for BDQ. Body weight, race, albumin, and concomitant medication were significant covariates affecting BDQ PK variation. With the increase of weight and albumin levels, the clearance (CL) of BDQ was gradually increased. The average CL value per body weight in children was 1.49-fold higher than that in adults. Black race patients had an 84% higher CL than other populations. Moreover, combined with rifampicin and rifapentine, BDQ had 378% and 296% higher clearance rates, respectively.

CONCLUSIONS

Body weight, race, albumin level, and concomitant medication may be important factors affecting patients' exposure differences. Further PPK studies of BDQ are needed to facilitate optimal dosing regimens.

The impact of menstrual cycle on the pharmacokinetics of antiseizure medications and lithium: a systematic review and meta-analysis

INTRODUCTION

Our aim was to quantify the impact of menstrual cycle phases on the pharmacokinetics of antiseizure medications (ASM) and lithium.

METHODS

A systematic literature search was conducted in PubMed/EMBASE in March 2024 for studies comparing levels of ASM and/or lithium in the early follicular and luteal phase. Concentration ratios between the follicular and the luteal phase were calculated. We performed a random-effects meta-analysis calculating between-timepoint differences in plasma concentration mean differences (MDs) and 95% confidence intervals (95% CIs). Subgroup analyses included cohorts stratified by the occurrence of catamenial exacerbation. Study quality was assessed using the ClinPK guidelines.

RESULTS

Fifteen studies investigating six ASM and lithium in 224 subjects were included. The highest concentration ratio was reported for carbamazepine (1.27, range 0.89-2.13) with an MD of 0.57 μg/mL, 95% CI: 0.41 to 0.72. Phenytoin concentration fluctuations were larger in subjects with (MD -3.51 μg/mL, 95% CI = -4.97 to -2.06) vs. without catamenial exacerbations (MD -1.18 μg/mL, 95% CI = -2.51 to 0.14, p = 0.02). Study quality was acceptable with an average rating score of 13.1.

CONCLUSIONS

Data do not suggest major changes in ASM pharmacokinetics across the menstrual cycle. Participants with vs. without catamenial exacerbation had larger phenytoin concentration decreases in the early follicular compared to the luteal phase.

PROTOCOL REGISTRATION

www.crd.york.ac.uk/prospero identifier is CRD42024527321.

Evolution of branched peptides as novel biomaterials

Branched peptide-based materials draw inspiration from dendritic structures to emulate the complex architecture of native tissues, aiming to enhance the performance of biomaterials in medical applications. These innovative materials benefit from several key features: they exhibit slower degradation rates, greater stiffness, and the ability to self-assemble. These properties are crucial for maintaining the structural integrity and functionality of the materials over time. By integrating bioactive peptides and natural polymers within their branched frameworks, these materials offer modularity and tunability and can accommodate a range of mechanical properties, degradation rates, and biological functions making them suitable for biomedical applications, including drug delivery systems, wound healing scaffolds, and tissue engineering constructs. In drug delivery, these materials can be engineered to release therapeutic agents in a controlled manner, enhancing the efficacy and safety of treatments. In wound healing, they provide a supportive environment which promotes rapid and efficient tissue repair. The combination of biomimetic design and functional adaptability makes branched peptide-based materials a promising candidate for the development of next-generation biomaterials, paving the way for significant advancements in healthcare.

Population Pharmacokinetics of Telmisartan in Healthy Subjects and Hypertensive Patients

BACKGROUND AND OBJECTIVE

Telmisartan exhibits significant pharmacokinetic (PK) variability, but it remains unclear whether its PK profile is altered in hypertensive patients. This study aimed to characterize telmisartan PKs by conducting a meta-analysis and developing a pooled population PK model based on data from healthy subjects and hypertensive patients.

METHODS

Relevant literature was identified by a systematic approach. Eighteen studies were selected for analysis, which included 394 healthy subjects receiving single doses of telmisartan, 190 healthy subjects receiving repeated doses, along with 295 hypertensive patients receiving repeated doses. Pooled population PK analysis incorporated 20 mean concentration-time profiles from 14 studies. Meta-analyses were performed using OpenMeta-Analyst, and population PK modeling was performed using NONMEM®.

RESULTS

Repeated telmisartan doses increased peak plasma concentrations. However, other noncompartmental PK parameters remained consistent across healthy and hypertensive populations. Telmisartan PKs were best described using a two-compartment model with first-order absorption and elimination in pooled analysis. Typical PK parameter values for apparent clearance (CL/F), apparent central and peripheral volumes of distribution (V1/F and V2/F), absorption rate constant (ka), and absorption lag time were 18.3 L/h, 20.7 L, 360 L, 0.183 h-1 and 0.228 h, respectively. Interindividual variabilities in CL/F, V1/F, and ka were 84%, 122%, and 106%, respectively. Covariate analysis revealed significantly lower CL/F (63.7%) and V1/F (90.3%) values in hypertensive patients than healthy subjects.

CONCLUSION

These findings quantified the variability of telmisartan PK profile and highlighted the differences between healthy individuals and hypertensive patients, suggesting the need for optimized dosage strategies to improve therapeutic outcomes.

Dose Evaluation and Optimization of Amoxicillin in Children Treated for Lyme Disease

Amoxicillin is commonly used to treat erythema migrans in the first stage of Lyme disease in children, with a recommended dose of 50 mg/kg/day, administered three times a day (q8h). This model-based simulation study aimed to determine whether splitting the same daily dose into two administrations (q12h) would provide comparable drug exposure. A pharmacokinetic model suitable for a pediatric population (age: 1 month to 18 years, weight: 4-80 kg) was selected through a literature review. Simulations were performed with 15,000 virtual patients receiving 16.67 mg/kg/dose q8h, 25 mg/kg/dose q12h, or other q12h dosing variations. The target therapeutic level was defined by the percentage of time that the unbound drug concentration remained above the minimum inhibitory concentration (% fT > MIC) specific to Borrelia burgdorferi, with MICs of 0.06, 0.25, 1, 2, and 4 mg/L, requiring at least 40% and 50% of time for effective treatment. Probability of target attainment (PTA) was considered acceptable if it exceeded 50%, allowing for comparison of dosing schedules. Results indicated that the 50 mg/kg/day divided q12h regimen provided similar drug exposure to the q8h regimen for MICs below 2 mg/L (PTAs >50%). For a MIC of 2 mg/L, PTA was achieved with a higher dose of 30 mg/kg/dose q12h. However, for a MIC of 4 mg/L, the PTA criterion was not met. These findings suggest that a twice-daily dosing of 25 mg/kg/dose provides comparable bactericidal activity to the thrice-daily regimen for MICs between 0.06 and 1 mg/L. This simplified regimen may improve adherence and treatment implementation in children.

Bridging the Gap: A Systematic Review with Expert Opinion on the Use of Dalbavancin for In-Label and Off-Label Indications in Pediatric Patients

OBJECTIVES

The aim of this work was to perform a systematic review assessing the pharmacokinetic/pharmacodynamic (PK/PD) properties of dalbavancin and the clinical use for in-label and off-label indications in pediatric patients.

METHODS

Two authors independently searched the PubMed-MEDLINE and Scopus databases and clinicaltrials.gov up to 20 November 2024, to retrieve randomized controlled trials (RCTs), observational studies, PK studies, and case series/reports assessing dalbavancin PK/PD properties or the clinical use for both in-label and off-label indications in pediatric patients. Data were independently extracted by the two authors, and the quality of the included studies was independently assessed by means of specific tools according to study design. Clinical success was selected as the primary outcome. Descriptive statistics were used for summarizing the retrieved data. Subgroup analysis according to PK/PD data, as well as in-label and off-label indications, was performed.

RESULTS

After screening 206 articles, nine studies were included in the systematic review (one RCT, three PK studies, and five case series/reports; n = 267). Dalbavancin exposure was 30% lower in pediatric patients compared to adults. In acute bacterial skin and skin structure infections (ABSSSIs), the overall clinical success of dalbavancin was 96.1-97.3% and 92.9% in RCT and case series, respectively. Bone and joint infections (60.7%) and central-line-associated bloodstream infections (14.3%) represented the most common dalbavancin off-label indications in pediatric patients. Overall, the clinical success for off-label indications was 92.9%. The rate of adverse events ranged from 7.1% to 10.7%.

CONCLUSIONS

Our systematic review summarized evidence concerning the PK/PD properties of dalbavancin and its use for in-label or off-label indications in pediatric patients. The available findings suggest that dalbavancin may be a valuable alternative for the management of ABSSSIs and/or off-label indications in pediatric patients according to efficacy and safety data, allowing for a potential minimized duration of hospital stay.

Population pharmacokinetics of cyclosporine A in hematopoietic stem cell transplant recipients: A systematic review

Cyclosporine A (CsA) is the prevalent immunosuppressive drug for preventing and treating graft-versus-host disease after hematopoietic stem cell transplantation (HSCT) in both children and adults. Population pharmacokinetic studies have identified covariates, owing to their large between-subject variability, facilitating individualized therapy. However, no review has summarized CsA's population pharmacokinetics post-HSCT. This systematic review aims to synthesize population pharmacokinetic studies of CsA therapy in HSCT recipients and explore influencing covariates. Thirteen studies, comprising five involving children, one involving both children and adults and seven involving adults, were included. The median apparent clearance in children surpassed that in adults, influenced notably by hematocrit level and body. While liver function impacted clearance, the effect was insignificant. Co-administration with cytochrome P450 enzyme inhibitors (e.g., fluconazole (Diflucan) or itraconazole) decreased drug clearance, whereas inducers (e.g., rifampicin or rifapentine) increased it. Area under the curve analysis is recommended over trough concentration-based monitoring for HSCT recipients on CsA. In cases of insufficient trough concentration, additional sampling points are recommended for improved area under the curve estimation. Further studies are needed to evaluate the optimal sampling points required for the area under the curve estimation in CsA therapy post-HSCT.

Artificial Intelligence and Machine Learning Applications to Pharmacokinetic Modeling and Dose Prediction of Antibiotics: A Scoping Review

Background and Objectives: The use of artificial intelligence (AI) and, in particular, machine learning (ML) techniques is growing rapidly in the healthcare field. Their application in pharmacokinetics is of potential interest due to the need to relate enormous amounts of data and to the more efficient development of new predictive dose models. The development of pharmacokinetic models based on these techniques simplifies the process, reduces time, and allows more factors to be considered than with classical methods, and is therefore of special interest in the pharmacokinetic monitoring of antibiotics. This review aims to describe the studies that use AI, mainly oriented to ML techniques, for dose prediction and analyze their results in comparison with the results obtained by classical methods. Furthermore, in the review, the techniques employed and the metrics to evaluate the precision are described to improve the compression of the results. Methods: A systematic search was carried out in the EMBASE, OVID, and PubMed databases and the results obtained were analyzed in detail. Results: Of the 13 articles selected, 10 were published in the last three years. Vancomycin was monitored in seven and none of the studies were performed on new antibiotics. The most used techniques were XGBoost and neural networks. Comparisons were conducted in most cases against population pharmacokinetic models. Conclusions: AI techniques offer promising results. However, the diversity in terms of the statistical metrics used and the low power of some of the articles make the overall assessment difficult. For now, AI-based ML techniques should be used in addition to classical population pharmacokinetic models in clinical practice.

Attaining Equity of Access to Research: Perspective on Research in Pregnancy and Breastfeeding Following Dolores Shockley Lecture at ASCPT2024

Everybody deserves access to evidence-based information to make decisions about their health. However, in many situations, clinical trial eligibility criteria mean that specific data do not exist for certain groups of individuals. These include pregnant and breastfeeding women, children, older people, those with hepatic and renal dysfunction, those with acute severe illness, and those with multiple co-morbidities and interacting medications. Resultantly, there may not be specific drug-dosing information for many patients who are treated in a clinical setting. The ASCPT2024 Dolores Shockley Lecture focused on the equitable access to research with a specific focus on clinical pharmacology studies in pregnancy and breastfeeding. To ensure the safe, effective use of medication in pregnancy and breastfeeding, women should be included in clinical trials and pharmacokinetic studies when a medication is anticipated to be used in women of childbearing potential. Community groups should be involved at all stages of research to maintain transparency and trust. This ensures that local priorities are investigated, that communities understand the findings and are empowered to make evidence-based decisions about their own medication use. Principles informing the design of such studies in pregnancy and lactation are in existence. Mathematical techniques such as physiologically-based pharmacokinetic modeling and stochastic simulation and estimation can enhance study design, and population pharmacokinetic modeling be used to understand variability within and between individuals. Data should be made findable, accessible, interoperable, and reusable (FAIR). Information (and where necessary, training) regarding the use of these approaches should be provided to decision-making stakeholders such as ethics committees and regulatory bodies.

Pharmacokinetics of ceftriaxone, gentamicin, meropenem and vancomycin in liver cirrhosis: a systematic review

OBJECTIVES

Patients with liver cirrhosis are prone to develop severe bacterial infections. Pharmacokinetics (PK) of antibiotics in cirrhosis are potentially affected by impaired biotransformation phases 0-3 and consequences of portal hypertension such as portovenous shunting, ascites formation and/or acute kidney injury (AKI). We aimed to elucidate to what extent PK of selected antibiotics and, therefore, dosage recommendations are affected in adults with cirrhosis.

METHODS

We performed a systematic search in PubMed, Embase, Cochrane and CINAHL on effects of cirrhosis on PK profiles of ceftriaxone, fosfomycin, gentamicin, meropenem, nitrofurantoin, piperacillin/tazobactam and vancomycin in adults. Antibiotics were selected based on the lack of specific dosing recommendations for adults with cirrhosis. We included studies reporting on ≥1 of the following PK parameters: AUC, half-life (t½), CL, volume of distribution (Vd), peak (Cmax) or trough concentrations (Cmin).

RESULTS

We identified 15 studies (ceftriaxone, n = 5; gentamicin, n = 3; meropenem n = 5; vancomycin, n = 2), including 379 patients with cirrhosis, of which two were of high quality. No eligible studies were identified for fosfomycin, nitrofurantoin or piperacillin/tazobactam. Ceftriaxone unbound concentration increased in cirrhosis, but was mitigated by increased renal CL. Gentamicin levels in ascitic fluid were comparable to those in plasma. Meropenem PK parameters were not altered in cirrhosis without AKI, but in the presence of AKI a decrease in CL was observed. In contrast, vancomycin CL decreased in advanced cirrhosis.

CONCLUSIONS

Available data in studies of mostly moderate quality suggest that PK of ceftriaxone, meropenem and vancomycin are altered in cirrhosis. More advanced PK studies are needed to provide specific dosing recommendations.

Population Pharmacokinetic Simulations for Dose Optimization of Tenofovir Disoproxil Fumarate in HIV-Infected Patients with Moderate-to-Severe Renal Impairment

Tenofovir disoproxil fumarate (TDF) requires dosage adjustments from the standard 300 mg once daily to every 48-96 h for moderate-to-severe renal impairment to avoid excessive exposure. However, this extended interval can lead to variable drug exposure and inconvenience. This study aimed to utilize the population pharmacokinetic (PPK) models to optimize TDF dosing regimens for HIV-infected patients with renal impairment. A systematic literature search was conducted across PubMed, Cochrane Library, and Scopus databases to identify relevant PPK studies of TDF in HIV-infected patients. From the included studies, the PPK models and associated parameters were extracted. Monte Carlo simulations (n = 2000) were performed to generate concentration-time profiles and derive PK parameters compared against reference ranges. For moderate renal impairment, the TDF 150 mg once-daily regimen achieved cumulative exposure comparable to the approved 300 mg every-other-day regimen. In severe renal impairment, TDF 75-100 mg administered once daily provided similar cumulative exposure as 300 mg every 72-96 h regimen while maintaining daily exposure comparable to the standard dose in patients with normal renal function. The approved extended dosing intervals of 72-96 h exhibited high drug exposure variability, initially resulting in supratherapeutic levels followed by suboptimal levels preceding the subsequent dose administration. In conclusion, administering smaller once-daily doses of TDF maintains consistent daily drug exposure comparable to the standard dose in patients with normal renal function while reducing variability in drug exposure, potentially mitigating the risk of nephrotoxicity. However, additional clinical studies are required to confirm these findings.

Pharmacokinetics of Psilocybin, a Tryptamine Alkaloid in Magic Mushroom (Psilocybe cubensis): A Systematic Review

Psilocybin, a major indole alkaloid found in magic mushrooms (Psilocybe cubensis), has recently drawn attention as a breakthrough therapy to treat major depressive disorder. This review aimed to summarize and identify knowledge gaps concerning their pharmacokinetic characteristics of psilocybin and its active metabolite, psilocin. Original studies related to pharmacokinetics of psilocybin conducted in vitro, animals, and humans were systematically collected from PubMed, Scopus, and ScienceDirect, from their inceptions to November 2023. Twenty articles were included in this work and assessed for study quality. A comprehensive review of the pharmacokinetics of psilocybin and psilocin in both animals and humans was performed. Psilocybin is considered a prodrug that is dephosphorylated to psilocin by alkaline phosphatase. Following ingestion, the peak psilocin plasma and brain levels were rapidly achieved in a dose-dependent manner. Psilocin is metabolized primarily through both Phase I and Phase II processes with the half-life of 2-3 hours. This review also identified lack of some pharmacokinetic related information and limitations of available research that may help direct future investigations to better understand the pharmacokinetics and improve study design including dose selection and dosage optimization.

A Systematic Review of the Pharmacokinetics and Pharmacodynamics of Novel Beta-Lactams and Beta-Lactam with Beta-Lactamase Inhibitor Combinations for the Treatment of Pneumonia Caused by Carbapenem-Resistant Gram-Negative Bacteria

BACKGROUND

Novel beta-lactams show activity against many multidrug-resistant Gram-negative bacteria that cause severe lung infections. Understanding pharmacokinetic/pharmacodynamic characteristics of these agents may help optimise outcomes in the treatment of pneumonia.

OBJECTIVES

To describe and appraise studies that report pulmonary pharmacokinetic and pharmacodynamic data of cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam and meropenem/vaborbactam.

METHODS

MEDLINE (PubMed), Embase, Web of Science and Scopus libraries were used for the literature search. Pulmonary population pharmacokinetic and pharmacokinetic/pharmacodynamic studies on adult patients receiving cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam, and meropenem/vaborbactam published in peer-reviewed journals were included. Two independent authors screened, reviewed and extracted data from included articles. A reporting guideline for clinical pharmacokinetic studies (ClinPK statement) was used for bias assessment. Relevant outcomes were included, such as population pharmacokinetic parameters and probability of target attainment of dosing regimens.

RESULTS

Twenty-four articles were included. There was heterogeneity in study methods and reporting of results, with diversity across studies in adhering to the ClinPK statement checklist. Ceftolozane/tazobactam was the most studied agent. Only two studies collected epithelial lining fluid samples from patients with pneumonia. All the other phase I studies enrolled healthy subjects. Significant population heterogeneity was evident among available population pharmacokinetic models. Probabilities of target attainment rates above 90% using current licensed dosing regiments were reported in most studies.

CONCLUSIONS

Although lung pharmacokinetics was rarely described, this review observed high target attainment using plasma pharmacokinetic data for all novel beta-lactams. Future studies should describe lung pharmacokinetics in patient populations at risk of carbapenem-resistant pathogen infections.

Development and application of a population pharmacokinetic model repository for caffeine dose tailoring in preterm infants

BACKGROUND

Considerable interindividual variability for the pharmacokinetics of caffeine in preterm infants has been demonstrated, emphasizing the importance of personalized dosing. This study aimed to develop and apply a repository of currently published population pharmacokinetic (PopPK) models of caffeine in preterm infants to facilitate model-informed precision dosing (MIPD).

RESEARCH DESIGN AND METHODS

Literature search was conducted using PubMed, Embase, Scopus, and Web of Science databases. Relevant publications were screened, and their quality was assessed. PopPK models were reestablished to develop the model repository. Covariate effects were evaluated and the concentration-time profiles were simulated. An online simulation and calculation tool was developed as an instance.

RESULTS

Twelve PopPK models were finally included in the repository. Preterm infants' age and body size, especially the postnatal age and current weight, were identified as the most clinically critical covariates. Simulated blood concentration-time profiles across these models were comparable. Caffeine citrate-dose regimen should be adjusted according to the age and body size of preterm infants. The developed online tool can be used to facilitate clinical decision-making.

CONCLUSIONS

The first developed repository of PopPK models for caffeine in preterm infants has a wide range of potential applications in the MIPD of caffeine.

Evaluation of Population Pharmacokinetic Models of Micafungin: Implications for Dosing Regimen Optimization in Critically Ill Patients

Micafungin (MFG) is a widely used echinocandin antifungal agent for treating invasive candidiasis, particularly in critically ill patients. However, its pharmacokinetics can be highly variable in this population. This systematic review aims to summarize population pharmacokinetic models and provide recommendations for its use in intensive care unit (ICU) patients. Monte Carlo simulations were implemented to compare pharmacokinetic parameters and probability of target attainment (PTA) against various Candida species. A total of 16 studies were included, of which 6 studies were conducted in adult ICU patients. The key covariates were body size, liver function, and sepsis-related organ failure assessment score (SOFA) score. The median MFG clearance in adult ICU patients was 30-51% higher than in adult non-ICU patients. For infections with C. albican with MIC below 0.016 mg/L, micafungin dosages of 100 and 150 mg/d were recommended for adult non-ICU and ICU patients, respectively. For C. tropicalis and C. glabrata, 200 and 250 mg/d were recommended, respectively. However, for C. krusei and C. parapsilosis, none of the tested dosage regimens achieved assumed PTA criteria within MIC ranges of 0.125-0.25 mg/L and 0.125-2 mg/L, respectively. Therefore, MFG dosage regimens in ICU and non-ICU patients should be tailored based on the Candida spp. and their respective MIC values.

Risk Factors Associated with Antibiotic Exposure Variability in Critically Ill Patients: A Systematic Review

(1) Background: Knowledge about the behavior of antibiotics in critically ill patients has been increasing in recent years. Some studies have concluded that a high percentage may be outside the therapeutic range. The most likely cause of this is the pharmacokinetic variability of critically ill patients, but it is not clear which factors have the greatest impact. The aim of this systematic review is to identify risk factors among critically ill patients that may exhibit significant pharmacokinetic alterations, compromising treatment efficacy and safety. (2) Methods: The search included the PubMed, Web of Science, and Embase databases. (3) Results: We identified 246 observational studies and ten clinical trials. The most studied risk factors in the literature were renal function, weight, age, sex, and renal replacement therapy. Risk factors with the greatest impact included renal function, weight, renal replacement therapy, age, protein or albumin levels, and APACHE or SAPS scores. (4) Conclusions: The review allows us to identify which critically ill patients are at a higher risk of not reaching therapeutic targets and helps us to recognize the extensive number of risk factors that have been studied, guiding their inclusion in future studies. It is essential to continue researching, especially in real clinical practice and with clinical outcomes.

Population pharmacokinetics of olanzapine in pediatric patients with psychiatric disorders

OBJECTIVE

To develop and validate a population pharmacokinetic (PPK) model of oral olanzapine in pediatric Chinese patients in order to individualize therapy in this population.

METHODS

A total of 897 serum concentrations from 269 pediatric patients taking oral olanzapine (ages 8-17 years) were collected. Demographic parameters, biological characteristics and concomitant medications were investigated as covariates. The data were analyzed using a nonlinear mixed-effects modeling approach. Bootstrapping (1000 runs), normalized prediction distribution error (NPDE), and external validation of 62 patients were employed. Simulations were performed to explore the individualized dosing regimens in various situations.

RESULTS

The one-compartment model with first-order absorption and elimination had an apparent clearance (CL/F) of 10.38 L/h, a distribution volume (V/F) of 9.41 L/kg and an absorption rate constant (Ka) fixed at 0.3 h-1. The equation was CL∕F (L∕h) = 10.38 × (body weight∕60)0.25 ×1.33 (if male) × 0.71 (if co-occurrence of infection) × 0.51 (if co-therapy with fluvoxamine) × 1.27 (if co-therapy with sertraline) × 1.43 (if co-therapy with valproate). The final model had satisfactory stability, robustness, and predictive ability. The results from a simulation suggested the oral olanzapine doses required for male and female pediatric patients weighing between 40 and 60 kg without co-medication were 10-15 mg/day and 7.5-10 mg/day, respectively, and dosage adjustments should be based on sex and body weight; and co-administrated with valproate, sertraline, or fluvoxamine.

CONCLUSION

This model may help individualize optimum dosing of oral olanzapine for pediatric patients.

The impact of pregnancy on the pharmacokinetics of antiseizure medications: A systematic review and meta-analysis of data from 674 pregnancies

OBJECTIVE

Increasing evidence suggests that the physiological changes of pregnancy may impact pharmacokinetics of antiseizure medications (ASM), and this may affect treatment outcomes. The aim of this study was to quantify the pregnancy impact on the ASM pharmacokinetics.

METHODS

A systematic literature search was conducted in PubMed/EMBASE in November 2022 and updated in August 2023 for studies comparing levels of ASM in the same individuals during pregnancy and in the preconception/postpartum period. Alteration ratios between the 3rd trimester and baseline were estimated. We also performed a random-effects meta-analysis calculating between-timepoint differences in mean differences (MDs) and 95% confidence intervals (95%CIs) for dose-adjusted plasma concentrations (C/D ratios). Study quality was assessed using the ClinPK guidelines.

RESULTS

A total of 65 studies investigating 15 ASMs in 674 pregnancies were included. The largest differences were reported for lamotrigine, oxcarbazepine and levetiracetam (alteration ratio 0.42, range 0.07-2.45, 0.42, range 0.08-0.82 and 0.52, range 0.04-2.77 respectively): accordingly, C/D levels were lower in the 3rd trimester for lamotrigine, levetiracetam and the main oxcarbazepine metabolite monohydroxycarbazepine (MD = -12.33 × 10-3, 95%CI = -16.08 to -8.58 × 10-3 (μg/mL)/(mg/day), p < 0.001, MD = -7.16 (μg/mL)/(mg/day), 95%CI = -9.96 to -4.36, p < 0.001, and MD = -4.87 (μg/mL)/(mg/day), 95%CI = -9.39 to -0.35, p = 0.035, respectively), but not for oxcarbazepine (MD = 1.16 × 10-3 (μg/mL)/(mg/day), 95%CI = -2.55 to 0.24 × 10-3, p = 0.10). The quality of studies was acceptable with an average rating score of 11.5.

CONCLUSIONS

Data for lamotrigine, oxcarbazepine (and monohydroxycarbazepine) and levetiracetam demonstrate major changes in pharmacokinetics during pregnancy, suggesting the importance of therapeutic drug monitoring to assist clinicians in optimizing treatment outcomes.

Population pharmacokinetic analyses of methotrexate in pediatric patients: a systematic review

BACKGROUND AND OBJECTIVES

Methotrexate is widely utilized in the chemotherapy of malignant tumors and autoimmune diseases in the pediatric population, but dosing can be challenging. Several population pharmacokinetic models were developed to characterize factors influencing variability and improve individualization of dosing regimens. However, significant covariates included varied across studies. The primary objective of this review was to summarize and discuss population pharmacokinetic models of methotrexate and covariates that influence pharmacokinetic variability in pediatric patients.

METHODS

Systematic searches were conducted in the PubMed and EMBASE databases from inception to 7 July 2023. Reporting Quality was evaluated based on a checklist with 31 items. The characteristics of studies and information for model construction and validation were extracted, summarized, and discussed.

RESULTS

Eighteen studies (four prospective studies and fourteen retrospective studies with sample sizes of 14 to 772 patients and 2.7 to 93.1 samples per patient) were included in this study. Two-compartment models were the commonly used structural models for methotrexate, and the clearance range of methotrexate ranged from 2.32 to 19.03 L/h (median: 6.86 L/h). Body size and renal function were found to significantly affect the clearance of methotrexate for pediatric patients. There were limited reports on the role of other covariates, such as gene polymorphisms and co-medications, in the pharmacokinetic parameters of methotrexate pediatric patients. Internal and external evaluations were used to assess the performance of the population pharmacokinetic models.

CONCLUSION

A more rigorous external evaluation needs to be performed before routine clinical use to select the appropriate PopPK model. Further research is necessary to incorporate larger cohorts or pool analyses in specific susceptible pediatric populations to improve the understanding of predicted exposure profiles and covariate identification.

Development and Quality Control of a Population Pharmacokinetic Model Library for Caspofungin

BACKGROUND

Caspofungin is an echinocandin antifungal agent commonly used as the first-line therapy for invasive candidiasis, salvage therapy for invasive aspergillosis, and empirical therapy for presumed fungal infections. Pharmacokinetic (PK) variabilities and suboptimal exposure have been reported for caspofungin, increasing the risk of insufficient efficacy.

OBJECTIVE

This work aimed to develop a caspofungin population pharmacokinetic (popPK) library and demonstrate its utility by assessing the probability of target attainment across diverse settings.

METHODS

We established a caspofungin popPK model library following a rigorous literature review, re-implementing selected models in R with rxode2. Quality control procedures included a comparison of different studies and assessing covariate impacts. Model libraries were primarily used to perform Monte Carlo simulations to estimate target attainment and guide personalized dosing in Candida infections.

RESULTS

A total of 13 models, one- or two-compartment models, were included. The most significant covariates were body size (weight and body surface area), liver function, and albumin level. The results show that children and adults showed considerable differences in pharmacokinetics. For C. albicans and C. parapsilosis, none of the populations achieved a PTA of ≥90% at their respective susceptible MIC values. In contrast, for C. glabrata, 70% of the adult studies reached a PTA of ≥90%, while all pediatric studies achieved the same PTA level.

CONCLUSION

At the recommended dosage, adult patients showed notably lower exposure to caspofungin compared to pediatric patients. Considering body size, liver function, and serum albumin is crucial when determining caspofungin dosage regimens. Furthermore, further research is required to comprehensively understand the pharmacokinetics of caspofungin in pediatric patients.

Population Pharmacokinetics of Intravenous Lidocaine in Adults: A Systematic Review

BACKGROUND

The establishment of optimal dosing regimens for intravenous (IV) lidocaine in the perioperative setting, aiming to balance effective pain relief with minimisation of potential side effects, is a topic of ongoing debate. This discussion stems from the significant variability in lidocaine's pharmacokinetic (PK) parameters and its relatively narrow safety margin. Population pharmacokinetic (popPK) modelling has emerged as a valuable tool for understanding the factors contributing to this observed variability in drug kinetics.

OBJECTIVES

This systematic review compiles the existing knowledge on lidocaine's PK properties and published popPK models, with a focus on significant covariates.

METHODS

A systematic search on Cochrane CENTRAL, Medline, and EMBASE was performed from inception to June 2023. Original clinical studies that administered IV lidocaine to adults and performed PK analyses using a nonlinear mixed effects modelling approach were included. The quality of the included studies was assessed by compliance with the Clinical Pharmacokinetics (ClinPK) statement checklist.

RESULTS

Seven studies were included, which involved a diverse adult population, including both volunteers and patients with various comorbidities. Lidocaine PK was primarily characterised by a two- or three-compartment model. The volume of distribution at steady state ranged from 66 to 194 L, and the total clearance ranged from 22 to 49 L/h. Despite adjusting for significant covariates like heart failure status, alpha-1-acid glycoprotein, duration of lidocaine infusion, and body weight, each study revealed substantial variability in PK parameters. The potential impact of hepatic or renal function biomarkers on these PK parameters calls for further investigation. Incomplete reporting of key aspects of developed models may hinder the models' reliability and clinical application.

CONCLUSION

The findings emphasise the importance of tailoring drug dosage to ensure the safe and effective use of intravenous lidocaine. Optimal design methodologies may be incorporated for a more efficient identification of important covariates. Utilising contemporary model evaluation methods like visual predictive checks and bootstrapping would enhance the robustness of popPK models and the reliability of their predictions. This comprehensive review advances our understanding of lidocaine's pharmacokinetics and lays the groundwork for further research in this critical area of perioperative pain management. Review protocol registered on 25 August 2023 in PROSPERO (CRD42023441113). This work was supported by the Fundamental Research Grant Scheme, the Ministry of Higher Education, Malaysia (FRGS/1/2020/SKK01/UM/02/2).

Have We Neglected to Study Target-Site Drug Exposure in Children? A Systematic Review of the Literature

BACKGROUND AND OBJECTIVE

Drug dosing should ideally be based on the drug concentrations at the target site, which, for most drugs, corresponds to the tissue. The exact influence of growth and development on drug tissue distribution is unclear. This systematic review compiles the current knowledge on the tissue distribution of systemically applied drugs in children, with the aim to identify priorities in tissue pharmacokinetic (PK) research in this population.

METHODS

A systematic literature search was performed in the MEDLINE and Embase databases.

RESULTS

Forty-two relevant articles were identified, of which 71% investigated antibiotics, while drug classes from the other studies were anticancer drugs, antifungals, anthelmintics, sedatives, thyreostatics, immunomodulators, antiarrhythmics, and exon skipping therapy. The majority of studies (83%) applied tissue biopsy as the sampling technique. Tonsil and/or adenoid tissue was most frequently examined (70% of all included patients). The majority of studies had a small sample size (median 9, range 1-93), did not include the youngest age categories (neonates and infants), and were of low reporting quality. Due to the heterogeneous data from different study compounds, dosing schedules, populations, and target tissues, the possibility for comparison of PK data between studies was limited.

CONCLUSION

The influence of growth and development on drug tissue distribution continues to be a knowledge gap, due to the paucity of tissue PK data in children, especially in the younger age categories. Future research in this field should be encouraged as techniques to safely investigate drug tissue disposition in children are available.

A Systematic Review of Clozapine Concentration-Dose Ratio from Therapeutic Drug Monitoring Studies in Children and Adolescents Treated with Clozapine for Mental Disorders

BACKGROUND

Therapeutic drug monitoring of clozapine in children and adolescents has received insufficient attention. Calculation of concentration-to-dose (C/D) ratios from trough steady-state concentrations estimate drug clearance.

METHODS

A systematic electronic literature search was conducted in 3 article databases from inception until January 10, 2023, and articles reporting clozapine concentrations in children and adolescents were retrieved. The pharmacokinetic quality of the studies was assessed, and clozapine C/D ratios were calculated using the sample mean clozapine dose and concentration.

RESULTS

Of the 37 articles of potential interest, only 7 reported clozapine trough and steady-state concentrations. After excluding case reports and a study confounded by fluvoxamine, 4 studies on psychosis from Europe and the United States were included. The clozapine C/D ratios were similar to published adult values and ranged from 0.82 to 1.24 with a weighted mean of 1.08 ng/mL per mg/d. The weighted means were 334 mg/d for the dose and 380 ng/mL for the concentration. The stratified analysis of the weighted mean clozapine C/D ratios from 2 studies showed lower values in 52 male (1.05 ng/mL per mg/d) than in 46 female (1.46 ng/mL per mg/d) children and adolescents, with values similar to those reported for European adult nonsmokers. Two female adolescents had high clozapine C/D ratios (2.54 ng/mL per mg/d), an Asian American patient with borderline obesity and a patient with intellectual disability with low dosage (mean = 102 mg/d) and concentration (mean = 55 ng/mL).

CONCLUSIONS

Reports on clozapine therapeutic drug monitoring in children and adolescents are limited in number and quality. Future studies should focus on basic pharmacokinetic issues, such as stratification by sex, smoking, and relevant comedications with inductive or inhibitory properties.

The impact of extracorporeal membrane oxygenation on antifungal pharmacokinetics: A systematic review

BACKGROUND AND OBJECTIVE

The use of extracorporeal membrane oxygenation (ECMO) as a cardiocirculatory or respiratory support has tremendously increased in critically ill patients. In the setting of ECMO support, invasive fungal infections are a severe cause of morbidity and mortality. This vulnerable population is at risk of suboptimal antifungal exposure due to an increased volume of distribution (Vd), drug sequestration and decreased clearance. Here, we aimed to summarize ex-vivo and clinical studies on the potential impact of ECMO on the pharmacokinetics (PK) of antifungal agents and dosing requirements.

METHODS

A systematic search of the literature within electronic databases PubMed and EMBASE was conducted from database inception to 30 April 2023. Inclusion criteria were as follows: critically ill patients receiving ECMO regardless of age and reporting at least one PK parameter.

RESULTS

Thirty-six studies met inclusion criteria, including seven ex-vivo experiments and 29 clinical studies evaluating three classes of antifungals: polyenes, triazoles and echinocandins. Based on the available ex-vivo PK data, we found a significant sequestration of highly lipophilic and protein-bound antifungals within the ECMO circuit such as voriconazole, posaconazole and micafungin but the PK of several antifungals remains to be addressed such as amphotericin B, isavuconazole and anidulafungin. Most clinical studies have shown increased Vd of some antifungals like fluconazole and micafungin, particularly in the pediatric population. Conflicting data exist about caspofungin exposure.

CONCLUSIONS

The available literature on the antifungal PK changes in ECMO setting is scarce. Whenever possible, therapeutic drug monitoring is highly advised to personalize antifungal therapy.

The extent of cytochrome P450 3A induction by antiseizure medications: A systematic review and network meta-analysis

OBJECTIVE

Antiseizure medications (ASMs) are commonly categorized as enzyme-inducers and non-enzyme-inducers based on their propensity to enhance the metabolism of concomitantly administered drugs. This systematic review and network meta-analysis aimed to rank ASMs as cytochrome P450 3A (CYP3A)-inducers based on a comparative assessment of ASM-induced reduction in the concentrations of sensitive substrate drugs.

METHODS

The protocol was registered with PROSPERO (International Prospective Register of Systematic Reviews; CRD42022335846), and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) standards were followed. We searched MEDLINE, Embase, and Cochrane until March 14, 2023 without an initial date restriction. Data were additionally obtained via the US Food and Drug Administration database. Studies had to be prospective, with ASM monotherapy for ≥5 days. The primary parameter was the magnitude of change in the area under the concentration-time curve of CYP3A substrates following treatment with the ASM. The standardized mean difference (SMD) was used as the point estimate for the indirect comparisons between ASMs using the pairwise method. Bias risk was assessed using the PKclin tool.

RESULTS

We identified 14 open-label, fixed-sequence studies with 370 participants. The effect size of 600 mg/day carbamazepine did not differ from those of 300 mg/day phenytoin (SMD = -.06, 95% confidence interval [CI] = -.18 to .07) and 200 mg/day cenobamate (SMD = -.11, 95% CI = -.26 to .04). Carbamazepine at 600 mg/day was the strongest CYP3A-inducer (P-score = .88), followed by carbamazepine 400 mg/day (.83), phenytoin 300 mg/day (.79), and cenobamate 200 mg/day (.73). Eslicarbazepine (800 mg/day) ranked higher than cenobamate 100 mg/day and oxcarbazepine 900 mg/day (.60, .39, and .37, respectively).

SIGNIFICANCE

Despite the limited number of studies, our network meta-analysis emphasizes that the magnitude of ASM effects on CYP3A substrate metabolism is a dose-dependent continuum. When possible, ASM classification as inducers should apply cutoff values tailored to the outcome. Prescribers should monitor plasma concentrations or clinical effects of CYP3A substrates and consider selecting concomitant medications accordingly.

Covariates in population pharmacokinetic studies of critically ill adults receiving β-lactam antimicrobials: a systematic review and narrative synthesis

Introduction

Population pharmacokinetic studies of β-lactam antimicrobials in critically ill patients derive models that inform their dosing. In non-linear mixed-effects modelling, covariates are often used to improve model fit and explain variability. We aimed to investigate which covariates are most commonly assessed and which are found to be significant, along with global patterns of publication.

Methods

We conducted a systematic review, searching MEDLINE, Embase, CENTRAL and Web of Science on 01 March 2023, including studies of critically ill adults receiving β-lactam antimicrobials who underwent blood sampling for population pharmacokinetic studies. We extracted and categorized all reported covariates and assessed reporting quality using the ClinPK checklist.

Results

Our search identified 151 studies with 6018 participants. Most studies reported observational cohorts (120 studies, 80%), with the majority conducted in high-income settings (136 studies, 90%). Of the 1083 identified covariate instances, 237 were unique; the most common categories were patient characteristics (n = 404), biomarkers (n = 206) and physiological parameters (n = 163). Only seven distinct commonly reported covariates (CLCR, weight, glomerular filtration rate, diuresis, need for renal replacement, serum albumin and C-reactive protein) were significant more than 20% of the time.

Conclusions

Covariates are most commonly chosen based on biological plausibility, with patient characteristics and biomarkers the most frequently investigated. We developed an openly accessible database of reported covariates to aid investigators with covariate selection when designing population pharmacokinetic studies. Novel covariates, such as sepsis subphenotypes, have not been explored yet, leaving a research gap for future work.

Insights into the population pharmacokinetics and pharmacodynamics of quetiapine: a systematic review

INTRODUCTION

Quetiapine exhibits notable pharmacokinetic and pharmacodynamic (PK/PD) variability, the origins of which are poorly understood. This systematic review summarizes published population PK/PD studies and identifies significant covariates accounting for this variability to inform precision dosing.

METHODS

We systematically searched the PubMed, Web of Science, and Embase databases and compared study characteristics, model parameters, and covariate effects. Visual predictive distributions were used to compare different models. Forest plots and Monte Carlo simulations were used to assess the influence of covariates.

RESULTS

Six population PK and three population PK/PD studies were included. The median apparent clearance in adults was 87.7 L/h. Strong and moderate cytochrome P450 3A4 inducers increased the apparent clearance approximately fourfold, while strong cytochrome P450 3A4 inhibitors reduced it by 93%. The half-maximum effect concentrations were 82.8 ng/mL for the Brief Psychiatric Rating Scale and 583 ng/mL for dopamine D2 receptor occupancy. Both treatment duration and quetiapine exposure were associated with weight gain.

CONCLUSIONS

Concurrent administration of potent or moderate CYP3A4 inducers and inhibitors need to be avoided in quetiapine-treated patients. When co-medication is required, it is recommended to adjust the dosage based on therapeutic drug monitoring. Additional research is warranted to delineate the dose-exposure-response relationships of quetiapine and active metabolite norquetiapine in pediatrics, geriatrics, hepatically-impaired patients, and women using contraceptives or are pregnant or menopausal.

PROSPERO REGISTRATION

CRD42023446654.

Parenteral Fosfomycin in Gastrointestinal Surgery: A Systematic Review

BACKGROUND

To investigate if perioperative parenteral administration of fosfomycin given before or during gastrointestinal surgery could protect against postoperative infectious complications and characterise the administration of fosfomycin and its harms.

METHODS

This systematic review included original studies on gastrointestinal surgery where parental administration of fosfomycin was given before or during surgery to≥5 patients. We searched three databases on March 24 2023 and registered the protocol before data extraction (CRD42020201268). Risk of bias was assessed with Cochrane Handbook risk of bias assessment tool or the Newcastle-Ottawa Scale. A narrative description was undertaken. For infectious complications, results from emergency and elective surgery were presented separately.

RESULTS

We included 15 unique studies, reporting on 1,029 patients that received fosfomycin before or during gastrointestinal surgery. Almost half of the studies were conducted in the 1980s to early 1990s, and typically a dose of 4 g fosfomycin was given before surgery co-administered with metronidazole and often repeated postoperatively. The risk of bias across studies was moderate to high. The rates of infectious complications were low after fosfomycin; the surgical site infection rate was 0-1% in emergency surgery and 0-10% in elective surgery. If reported, harms were few and mild and typically related to the gastrointestinal system.

CONCLUSION

There were few postoperative infectious complications after perioperative parenteral administration of one or more doses of 4 g fosfomycin supplemented with metronidazole in various gastrointestinal procedures. Fosfomycin was associated with few and mild harms.

Grading the level of evidence of neonatal pharmacotherapy: midazolam and phenobarbital as examples

BACKGROUND

Many drugs are used off-label or unlicensed in neonates. This does not mean they are used without evidence or knowledge. We aimed to apply and evaluate the Grading and Assessment of Pharmacokinetic-Pharmacodynamic Studies (GAPPS) scoring system for the level of evidence of two commonly used anti-epileptic drugs.

METHODS

Midazolam and phenobarbital as anti-epileptics were evaluated with a systematic literature search on neonatal pharmacokinetic (PK) and/or pharmacodynamic [PD, (amplitude-integrated) electroencephalography effect] studies. With the GAPPS system, two evaluators graded the current level of evidence. Inter-rater agreement was assessed for dosing evidence score (DES), quality of evidence (QoE), and strength of recommendation (REC).

RESULTS

Seventy-two studies were included. DES scores 4 and 9 were most frequently used for PK, and scores 0 and 1 for PD. Inter-rater agreements on DES, QoE, and REC ranged from moderate to very good. A final REC was provided for all PK studies, but only for 25% (midazolam) and 33% (phenobarbital) of PD studies.

CONCLUSIONS

There is a reasonable level of evidence concerning midazolam and phenobarbital PK in neonates, although using a predefined target without integrated PK/PD evaluation. Further research is needed on midazolam use in term neonates with therapeutic hypothermia, and phenobarbital treatment in preterms.

IMPACT

There is a reasonable level of evidence concerning pharmacotherapy of midazolam and phenobarbital in neonates. Most evidence is however based on PK studies, using a predefined target level or concentration range without integrated, combined PK/PD evaluation. Using the GAPPS system, final strength of recommendation could be provided for all PK studies, but only for 25% (midazolam) to 33% (phenobarbital) of PD studies. Due to the limited PK observations of midazolam in term neonates with therapeutic hypothermia, and of phenobarbital in preterm neonates these subgroups can be identified for further research.

Using population pharmacokinetics to optimize initial vancomycin dosing guidelines for neonates to treat sepsis caused by coagulase-negative staphylococcus

INTRODUCTION

Vancomycin dosing tailored for newborns is challenging due to the significant influence of maturation and organ function on pharmacokinetics. Population pharmacokinetic (popPK) models can be used to improve target attainment in neonates.

OBJECTIVES

The primary objective was to derive and evaluate a popPK model of intravenous vancomycin for neonates. Second, the predictive performance of this popPK model was compared with published popPK models.

METHODS

This is a retrospective cohort study of neonates admitted to the neonatal intensive care unit receiving intravenous vancomycin. A popPK model was derived with 70% of the dataset using a nonlinear mixed effects modeling method. The predictive performance of the current popPK model was validated and compared with 22 published popPK models using the remaining 30% of the dataset. Monte Carlo simulations (MCS) were performed to derive optimal dosing regimens to treat neonatal sepsis caused by coagulase-negative staphylococci (CoNS).

RESULTS

Among 655 vancomycin courses from 448 neonates, 78% of vancomycin trough concentrations were outside target range (10-15 mg/L) for central nervous system infections and 43% were outside target range (5-12 mg/L) for other infections using the institution's vancomycin dosing. A one-compartment model best described the observed data with a mean clearance of 0.11 ± 0.03 L/kg/h and volume of distribution (V) of 1.02 ± 0.08 L/kg. Body weight (WT), postmenstrual age (PMA), and serum creatinine (SCr) were significant covariates associated with clearance (p < 0.001) and body WT was a significant covariate associated with V (p = 0.009). Our study's popPK model has similar or better accuracy and precision than other published models. MCS-derived vancomycin doses from the validated model achieved >90% target attainment for a steady state through target range of 10-15 mg/L in the majority of PMA and SCr categories (78%) to treat CoNS sepsis.

CONCLUSION

A vancomycin dosing guideline derived from a validated popPK model in neonates with CoNS sepsis is recommended to improve target attainment.

The pharmacokinetics of 38% silver diamine fluoride in healthy children with dental caries: a quasi-experimental study

PURPOSE

Silver diamine fluoride (SDF) is a medication used for the arrestment of dental caries. This study aims to determine the pharmacokinetics (PK) of silver and fluoride following SDF application in healthy children with dental caries.

METHODS

A total of 15 subjects, aged 4 to 10 years, with at least one cavity on a primary tooth, were recruited for this study. Urine samples were collected at baseline, first 24 h (F1) and second 24 h (F2) after SDF treatment for analysis of silver and fluoride content. Hair samples were also collected at baseline and at 7, 14, 30, 60, 75, and 90 days after SDF treatment to analyze silver content.

RESULTS

Participants with under or over-collection of urine, or failure to provide urine collection were excluded for fluoride analysis. As a result, eight subjects' urine samples were eligible for fluoride analysis. Significant correlations were observed between baseline urinary fluoride levels and F1/F2 levels. Pairwise comparisons from Friedman's test showed significant differences between baseline and F1 fluoride levels. For silver analysis, 15 subjects were studied. F1 urinary silver levels were higher than baseline and F2 levels. Subsequent to SDF treatment, hair silver levels displayed fluctuations around the baseline. None of the participants reported adverse effects, and all caries teeth ceased progression within 30 days.

CONCLUSIONS

The urinary fluoride levels after SDF treatment, although higher, were not clinically significant. Urinary and hair silver levels were negligible. Therefore, SDF appears safe to be used among children.

Impact of Various Estimated Glomerular Filtration Rate Equations on the Pharmacokinetics of Meropenem in Critically Ill Adults

IMPORTANCE

Meropenem dosing is typically guided by creatinine-based estimated glomerular filtration rate (eGFR), but creatinine is a suboptimal GFR marker in the critically ill.

OBJECTIVES

This study aimed to develop and qualify a population pharmacokinetic model for meropenem in critically ill adults and to determine which eGFR equation based on creatinine, cystatin C, or both biomarkers best improves model performance.

DESIGN SETTING AND PARTICIPANTS

This single-center study evaluated adults hospitalized in an ICU who received IV meropenem from 2018 to 2022. Patients were excluded if they had acute kidney injury, were on kidney replacement therapy, or were treated with extracorporeal membrane oxygenation. Two cohorts were used for population pharmacokinetic modeling: a richly sampled development cohort (n = 19) and an opportunistically sampled qualification cohort (n = 32).

MAIN OUTCOMES AND MEASURES

A nonlinear mixed-effects model was developed using parametric methods to estimate meropenem serum concentrations.

RESULTS

The best-fit structural model in the richly sampled development cohort was a two-compartment model with first-order elimination. The final model included time-dependent weight normalized to a 70-kg adult as a covariate for volume of distribution (Vd) and time-dependent eGFR for clearance. Among the eGFR equations evaluated, eGFR based on creatinine and cystatin C expressed in mL/min best-predicted meropenem clearance. The mean (se) Vd in the final model was 18.2 (3.5) liters and clearance was 11.5 (1.3) L/hr. Using the development cohort as the Bayesian prior, the opportunistically sampled cohort demonstrated good accuracy and low bias.

CONCLUSIONS AND RELEVANCE

Contemporary eGFR equations that use both creatinine and cystatin C improved meropenem population pharmacokinetic model performance compared with creatinine-only or cystatin C-only eGFR equations in adult critically ill patients.

Pharmacokinetic and pharmacodynamic considerations for antifungal therapy optimisation in the treatment of intra-abdominal candidiasis

Intra-abdominal candidiasis (IAC) is one of the most common of invasive candidiasis observed in critically ill patients. It is associated with high mortality, with up to 50% of deaths attributable to delays in source control and/or the introduction of antifungal therapy. Currently, there is no comprehensive guidance on optimising antifungal dosing in the treatment of IAC among the critically ill. However, this form of abdominal sepsis presents specific pharmacokinetic (PK) alterations and pharmacodynamic (PD) challenges that risk suboptimal antifungal exposure at the site of infection in critically ill patients. This review aims to describe the peculiarities of IAC from both PK and PD perspectives, advocating an individualized approach to antifungal dosing. Additionally, all current PK/PD studies relating to IAC are reviewed in terms of strength and limitations, so that core elements for the basis of future research can be provided.

Population pharmacokinetic model of cefepime for critically ill adults: a comparative assessment of eGFR equations

Cefepime exhibits highly variable pharmacokinetics in critically ill patients. The purpose of this study was to develop and qualify a population pharmacokinetic model for use in the critically ill and investigate the impact of various estimated glomerular filtration rate (eGFR) equations using creatinine, cystatin C, or both on model parameters. This was a prospective study of critically ill adults hospitalized at an academic medical center treated with intravenous cefepime. Individuals with acute kidney injury or on kidney replacement therapy or extracorporeal membrane oxygenation were excluded. A nonlinear mixed-effects population pharmacokinetic model was developed using data collected from 2018 to 2022. The 120 included individuals contributed 379 serum samples for analysis. A two-compartment pharmacokinetic model with first-order elimination best described the data. The population mean parameters (standard error) in the final model were 7.84 (0.24) L/h for CL1 and 15.6 (1.45) L for V1. Q was fixed at 7.09 L/h and V2 was fixed at 10.6 L, due to low observed interindividual variation in these parameters. The final model included weight as a covariate for volume of distribution and the eGFRcr-cysC (mL/min) as a predictor of drug clearance. In summary, a population pharmacokinetic model for cefepime was created for critically ill adults. The study demonstrated the importance of cystatin C to prediction of cefepime clearance. Cefepime dosing models which use an eGFR equation inclusive of cystatin C are likely to exhibit improved accuracy and precision compared to dosing models which incorporate an eGFR equation with only creatinine.

Antimicrobial pharmacokinetics and dosing in critically ill adults receiving prolonged intermittent renal replacement therapy: A systematic review

Prolonged intermittent renal replacement therapy (PIRRT) is gaining popularity as a renal replacement modality in intensive care units, but there is a relative lack of guidance regarding antimicrobial clearance and dosing when compared with other modalities. The objectives of this systematic review were to: (1) identify and describe the pharmacokinetics (PK) of relevant antimicrobials used in critically ill adults receiving PIRRT, (2) evaluate the quality of evidence supporting these data, and (3) propose dosing recommendations based on the synthesis of these data. A search strategy for multiple databases was designed and executed to identify relevant published evidence describing the PK of antimicrobials used in critically ill adults receiving PIRRT. Quality assessment, evaluation of reporting, and relevant data extraction were conducted in duplicate. Synthesis of PK/pharmacodynamic (PD) outcomes, dosing recommendations from study authors, and physicochemical properties of included antibiotics were assessed by investigators in addition to the quality of evidence to develop dosing recommendations. Thirty-nine studies enrolling 452 patients met criteria for inclusion and provided PK and/or PD data for 20 antimicrobials in critically ill adults receiving PIRRT. Nineteen studies describe both PK and PD outcomes. Vancomycin (12 studies, 171 patients), meropenem (7 studies, 84 patients), and piperacillin/tazobactam (5 studies, 56 patients) were the most frequent antimicrobials encountered. The quality of evidence was deemed strong for 7/20 antimicrobials, and strong dosing recommendations were determined for 9/20 antimicrobials. This systematic review updates and addresses issues of quality in previous systematic reviews on this topic. Despite an overall low quality of evidence, strong recommendations were able to be made for almost half of the identified antimicrobials. Knowledge gaps persist for many antimicrobials, and higher quality studies (i.e., population PK studies with assessment of PD target attainment) are needed to address these gaps.

Pharmacokinetics of Commonly Used Antimicrobials in Critically Ill Pediatric Patients During Extracorporeal Membrane Oxygenation: A Systematic Review

PURPOSE

Adequate dosing of antimicrobials is critical to properly treat infections and limit development of resistance and adverse effects. Limited guidance exist for antimicrobial dosing adjustments in patients requiring extracorporeal membrane oxygenation (ECMO) therapy, particularly in the pediatric population. A systematic review was conducted to delineate the pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobials in critically ill neonates and children requiring ECMO therapy.

METHODS

Medline, EMBASE, Global Health and All EBM Reviews databases were queried. Grey literature was examined. All clinical studies reporting PK/PD parameters of antimicrobials in critically ill pediatric patients treated with ECMO were included, except for case reports and congress abstracts. Two independent reviewers applied the inclusion and exclusion criteria. Reviewers were then paired to independently extract data and evaluate the methodological quality of studies using the ROBINS-I tool and the compliance with ClinPK reporting guidelines. Patient and study characteristics, key PK/PD findings, details of ECMO circuits and co-treatments were summarized qualitatively. Broad dosing recommendations were formulated based on the available data for specific antimicrobials.

RESULTS

Twenty-nine clinical studies were included; most were observational and uncontrolled. Patient characteristics and co-treatments were often missing. The effect of ECMO on PK/PD parameters of antimicrobials varied depending on the drugs and population studied. It was only possible to formulate dosing recommendations for a few antimicrobials given the paucity of data, its overall low quality and heterogeneity in reporting.

CONCLUSION

Limited data exists on the PK/PD of antimicrobials during ECMO therapy in the pediatric population. Rigorously designed population PK studies are required to establish empiric dosing guidelines for antimicrobials in patients requiring this therapeutic modality. The use of therapeutic drug monitoring for antimicrobials in pediatric patients on ECMO should be encouraged to optimize dosing.

TRIAL REGISTRY

PROSPERO registration number: CRD42018099992 (Registered: July 24th 2018).

Pharmacokinetic analysis across studies to drive knowledge-integration: A tutorial on individual patient data meta-analysis (IPDMA)

Answering challenging questions in drug development sometimes requires pharmacokinetic (PK) data analysis across different studies, for example, to characterize PKs across diverse regions or populations, or to increase statistical power for subpopulations by combining smaller size trials. Given the growing interest in data sharing and advanced computational methods, knowledge integration based on multiple data sources is increasingly applied in the context of model-informed drug discovery and development. A powerful analysis method is the individual patient data meta-analysis (IPDMA), leveraging systematic review of databases and literature, with the most detailed data type of the individual patient, and quantitative modeling of the PK processes, including capturing heterogeneity of variance between studies. The methodology that should be used in IPDMA in the context of population PK analysis is summarized in this tutorial, highlighting areas of special attention compared to standard PK modeling, including hierarchical nested variability terms for interstudy variability, and handling between-assay differences in limits of quantification within a single analysis. This tutorial is intended for any pharmacological modeler who is interested in performing an integrated analysis of PK data across different studies in a systematic and thorough manner, to answer questions that transcend individual primary studies.

Pharmacokinetic Properties of Dapagliflozin in Hemodialysis and Peritoneal Dialysis Patients

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors attenuate incident cardiovascular outcomes, irrespective of baseline GFR, in conservatively managed CKD. As this condition inexorably progresses to demanding KRT, drug withdrawal is supported by the current lack of evidence of safety of SGLT2 inhibitors in dialysis.

METHODS

This study was a prospective, single-center, open-label trial ( ClinicalTrials.gov identifier: NCT05343078 ) aimed at assessing the pharmacokinetic properties and safety of dapagliflozin in patients with kidney failure on regular dialysis regimens compared with those with type 2 diabetes and age- and sex-matched controls with normal kidney function. Peripheral blood samples were collected from both groups every 30 minutes for 4 hours and again after 48 hours after ingestion of dapagliflozin 10 mg, which occurred immediately before dialysis session initiation in the kidney failure group. This protocol occurred in drug-naïve patients and again after six daily doses of dapagliflozin to assess whether the drug had accumulated. The plasma and dialysate levels of dapagliflozin at each time point were determined by liquid chromatography and used to calculate pharmacokinetics parameters (peak concentration [C max ] and area under the plasma concentration-versus-time curve) for each participant.

RESULTS

Dapagliflozin C max was 117 and 97.6 ng/ml in the kidney failure and control groups, respectively, whereas the corresponding accumulation ratios were 26.7% and 9.5%. No serious adverse events were reported for either group. Dapagliflozin recovered from dialysate corresponded to 0.10% of the administered dose.

CONCLUSIONS

In patients with kidney failure on dialysis, dapagliflozin was well tolerated, was slightly dialyzable, and had nonaccumulating pharmacokinetic properties.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Pharmacokinetics and Dialyzability of Dapagliflozin in Dialysis Patients (DARE-ESKD 1), NCT05343078.

A systematic review on maternal-to-infant transfer of drugs through breast milk during the treatment of malaria, tuberculosis, and neglected tropical diseases

BACKGROUND

Exclusive breastfeeding of infants under 6 months of age is recommended by the World Health Organization. In 2021, over 300 million combined incident cases of malaria, tuberculosis, and neglected tropical diseases (NTDs) were reported, predominantly in low-income countries. For many of the drugs used as first-line treatments for these conditions, there is limited knowledge on infant exposure through breastfeeding with poorly understood consequences. This review summarized available knowledge on mother-to-infant transfer of these drugs to inform future lactation pharmacokinetic studies.

METHODOLOGY

A list of first-line drugs was generated from the latest WHO treatment guidelines. Using standard online databases, 2 independent reviewers searched for eligible articles reporting lactation pharmacokinetics studies and extracted information on study design, participant characteristics, and the mathematical approach used for parameter estimation. A third reviewer settled any disagreements between the 2 reviewers. All studies were scored against the standardized "ClinPK" checklist for conformity to best practices for reporting clinical pharmacokinetic studies. Simple proportions were used to summarize different study characteristics.

FINDINGS

The most remarkable finding was the scarcity of lactation pharmacokinetic data. Only 15 of the 69 drugs we listed had lactation pharmacokinetics fully characterized. Most studies enrolled few mothers, and only one evaluated infant drug concentrations. Up to 66% of the studies used non-compartmental analysis to estimate pharmacokinetic parameters rather than model-based compartmental analysis. Unlike non-compartmental approaches, model-based compartmental analysis provides for dynamic characterization of individual plasma and breast milk concentration-time profiles and adequately characterizes variability within and between individuals, using sparsely sampled data. The "ClinPK" checklist inadequately appraised the studies with variability in the number of relevant criteria across different studies.

CONCLUSIONS/SIGNIFICANCE

A consensus is required on best practices for conducting and reporting lactation pharmacokinetic studies, especially in neglected diseases such as malaria, tuberculosis, and NTDs, to optimize treatment of mother-infant pairs.

Population Pharmacokinetic Model of Intravenous Busulfan in Hematopoietic Cell Transplantation: Systematic Review and Comparative Simulations

BACKGROUND

Busulfan is commonly used in the chemotherapy prior to hematopoietic cell transplantation (HCT). Busulfan has a narrow therapeutic window and a well-established exposure-response relationship with important clinical outcomes. Model-informed precision dosing (MIPD) based on population pharmacokinetic (popPK) models has been implemented in the clinical settings. We aimed to systematically review existing literature on popPK models of intravenous busulfan.

METHODS

We systematically searched Ovid MEDLINE, EMBASE, Cochrane Library, Scopus, and Web of Science databases from inception to December 2022 to identify original popPK models (nonlinear mixed-effect modeling) of intravenous busulfan in HCT population. Model-predicted busulfan clearance (CL) was compared using US population data.

RESULTS

Of the 44 eligible popPK studies published since 2002, 68% were developed predominantly in children, 20% in adults, and 11% in both children and adults. The majority of the models were described using first-order elimination or time-varying CL (69% and 26%, respectively). All but three included a body-size descriptor (e.g., body weight, body surface area). Other commonly included covariates were age (30%) and GSTA1 variant (15%). Median between-subject and between-occasion variabilities of CL were 20% and 11%, respectively. Between-model variabilities in predicted median CL were < 20% in all of the weight tiers (10-110 kg) in the simulation based on US population data.

CONCLUSION

Busulfan PK is commonly described using a first-order elimination or time-varying CL. A simple model with limited covariates were generally sufficient to attain relatively small unexplained variabilities. However, therapeutic drug monitoring may still be necessary to attain a narrow target exposure.

Transfer of anticonvulsants and lithium into amniotic fluid, umbilical cord blood & breast milk: A systematic review & combined analysis

OBJECTIVE

Data on the ability of anticonvulsants and lithium to enter fetal and newborn circulation has become increasingly available; here we estimated penetration ratios in a series of matrices from combined samples of pregnant/breastfeeding women treated with anticonvulsants or lithium.

METHODS

We conducted a systematic literature search in PubMed/EMBASE for studies with concentrations of anticonvulsants/lithium from maternal blood, amniotic fluid, umbilical cord blood and/or breast milk. Penetration ratios were calculated by dividing the concentrations in amniotic fluid, umbilical cord plasma or breast milk by the maternal concentrations. When data from multiple studies were available, we calculated combined penetration ratios, weighting studies' mean by study size.

RESULTS

Ninety-one eligible studies for brivaracetam, carbamazepine, clonazepam, ethosuximide, gabapentin, lacosamide, lamotrigine, levetiracetam, lithium, oxcarbazepine, perampanel, phenobarbital, phenytoin, pregabalin, primidone, topiramate, valproate, vigabatrin and zonisamide were identified. For amniotic fluid, the highest penetration ratios were estimated for levetiracetam (mean 3.56, range 1.27-5.85, n = 2) and lowest for valproate (mean 0.11, range 0.02-1.02, n = 57). For umbilical cord plasma, oxcarbazepine had the highest ratio (mean 1.59, range 0.11-4.33, n = 12) with clonazepam having the lowest (mean 0.55, range 0.52-0.59, n = 2). For breast milk, the highest ratios were observed for oxcarbazepine (mean 3.75, range 0.5-7.0, n = 2), whereas the lowest were observed for valproate (mean 0.04, range 0.01-0.22, n = 121).

DISCUSSION

We observed substantial variability between anticonvulsants and lithium regarding their ability to enter fetal/newborn circulation. Assessing concentrations of anticonvulsants and lithium in maternal samples can provide a surrogate of fetal/infant exposure, although patterns of concentration-dependent effects for maternal/neonatal safety are lacking.

Is the Pharmacokinetics of First-Line Anti-TB Drugs a Cause of High Mortality Rates in TB Patients Admitted to the ICU? A Non-Compartmental Pharmacokinetic Analysis

BACKGROUND

Patients with tuberculosis (TB) may develop multi-organ failure and require admission to intensive care. In these cases, the mortality rates are as high as 78% and may be caused by suboptimal serum concentrations of first-line TB drugs. This study aims to compare the pharmacokinetics of oral rifampin, isoniazid, pyrazinamide and ethambutol patients in intensive care units (ICU) to outpatients and to evaluate drug serum concentrations as a potential cause of mortality.

METHODS

A prospective pharmacokinetic (PK) study was performed in Amazonas State, Brazil. The primary PK parameters of outpatients who achieved clinical and microbiological cure were used as a comparative target in a non-compartmental analysis.

RESULTS

Thirteen ICU and twenty outpatients were recruited. The clearance and volume of distribution were lower for rifampin, isoniazid, pyrazinamide and ethambutol. ICU thirty-day mortality was 77% versus a cure rate of 89% in outpatients.

CONCLUSIONS

ICU patients had a lower clearance and volume of distribution for rifampin, isoniazid, pyrazinamide and ethambutol compared to the outpatient group. These may reflect changes to organ function, impeded absorption and distribution to the site of infection in ICU patients and have the potential to impact clinical outcomes.

Population pharmacokinetic analyses of tacrolimus in non-transplant patients: a systematic review

BACKGROUND AND OBJECTIVES

Tacrolimus (TAC) has been increasingly used in patients with non-transplant settings. Because of its large between-subject variability, several population pharmacokinetic (PPK) studies have been performed to facilitate individualized therapy. This review summarized published PPK models of TAC in non-transplant patients, aiming to clarify factors affecting PKs of TAC and identify the knowledge gap that may require further research.

METHODS

The PubMed, Embase databases, and Cochrane Library, as well as related references, were searched from the time of inception of the databases to February 2023, to identify TAC population pharmacokinetic studies modeled in non-transplant patients using a non-linear mixed-effects modeling approach.

RESULTS

Sixteen studies, all from Asian countries (China and Korea), were included in this study. Of these studies, eleven and four were carried out in pediatric and adult patients, respectively. One-compartment models were the commonly used structural models for TAC. The apparent clearance (CL/F) of TAC ranged from 2.05 to 30.9 L·h^-1 (median of 14.9 L·h^-1). Coadministered medication, genetic factors, and weight were the most common covariates affecting TAC-CL/F, and variability in the apparent volume of distribution (V/F) was largely explained by weight. Coadministration with Wuzhi capsules reduced CL/F by about 19 to 43%. For patients with CYP3A5*1*1 and *1*3 genotypes, the CL/F was 39-149% higher CL/F than patients with CYP3A5*1*1.

CONCLUSION

The optimal TAC dosage should be adjusted based on the patient's co-administration, body weight, and genetic information (especially CYP3A5 genotype). Further studies are needed to assess the generalizability of the published models to other ethnic groups. Moreover, external validation should be frequently performed to improve the clinical practicality of the models.

Optimization of β-Lactam Dosing Regimens in Neonatal Infections: Continuous and Extended Administration versus Intermittent Administration

BACKGROUND AND OBJECTIVE

In neonates, β-Lactam antibiotics are almost exclusively administered by intermittent infusion. However, continuous or prolonged infusion may be more beneficial because of the time-dependent antibacterial activity. In this pharmacokinetic/pharmacodynamic simulation study, we aimed to compare treatment with continuous, extended and intermittent infusion of β-lactam antibiotics for neonates with infectious diseases.

METHODS

We selected population pharmacokinetic models of penicillin G, amoxicillin, flucloxacillin, cefotaxime, ceftazidime and meropenem, and performed a Monte Carlo simulation with 30,000 neonates. Four different dosing regimens were simulated: intermittent infusion in 30 min, prolonged infusion in 4 h, continuous infusion, and continuous infusion with a loading dose. The primary endpoint was 90% probability of target attainment (PTA) for 100% ƒT>MIC during the first 48 h of treatment.

RESULTS

For all antibiotics except cefotaxime, continuous infusion with a loading dose resulted in a higher PTA compared with other dosing regimens. Sufficient exposure (PTA >90%) using continuous infusion with a loading dose was reached for amoxicillin (90.3%), penicillin G (PTA 98.4%), flucloxacillin (PTA 94.3%), cefotaxime (PTA 100%), and ceftazidime (PTA 100%). Independent of dosing regimen, higher meropenem (PTA for continuous infusion with a loading dose of 85.5%) doses might be needed to treat severe infections in neonates. Ceftazidime and cefotaxime dose might be unnecessarily high, as even with dose reductions, a PTA > 90% was retained.

CONCLUSIONS

Continuous infusion after a loading dose leads to a higher PTA compared with continuous, intermittent or prolonged infusion, and therefore has the potential to improve treatment with β-lactam antibiotics in neonates.

External evaluation and systematic review of population pharmacokinetic models for high-dose methotrexate in cancer patients

Several population pharmacokinetic (PPK) models have been established to optimize the therapeutic regimen and reduce the toxicity of high-dose methotrexate (HDMTX) in patients with cancer. However, their predictive performance when extrapolated to different clinical centers was unknown. In this study, we aimed to externally evaluate the predictive ability of HDMTX PPK models and determine the potential influencing factors. We searched the literature and determined the predictive performance of the selected models using methotrexate concentrations in 721 samples from 60 patients in the First Affiliated Hospital of the Navy Medical University. Prediction-based diagnostics and simulation-based normalized prediction distribution errors (NPDE) were used to evaluate the predictive performance of the models. The influence of prior information was also assessed using Bayesian forecasting, and the potential factors affecting model predictability were investigated. Thirty models extracted from published PPK studies were assessed. Prediction-based diagnostics showed that the number of compartments potentially influenced model transferability, and simulation-based NPDE indicated model misspecification. Bayesian forecasting significantly improved the predictive performance of the models. Various factors, including bioassays, covariates, and population diagnosis, influence model extrapolation. The published models were unsatisfactory for all prediction-based diagnostics, except for the 24 h methotrexate concentration monitoring and simulation-based diagnostics, making them inappropriate for direct extrapolation. Moreover, Bayesian forecasting combined therapeutic drug monitoring could improve the predictive performance of the models.

A Systematic Review on Antimicrobial Pharmacokinetic Differences between Asian and Non-Asian Adult Populations

While the relevance of inter-ethnic differences to the pharmacokinetic variabilities of antimicrobials has been reported in studies recruiting healthy subjects, differences in antimicrobial pharmacokinetics between Asian and non-Asian patients with severe pathologic conditions require further investigation. For the purpose of describing the potential differences in antimicrobial pharmacokinetics between Asian and non-Asian populations, a systematic review was performed using six journal databases and six theses/dissertation databases (PROSPERO record CRD42018090054). The pharmacokinetic data of healthy volunteers and non-critically ill and critically ill patients were reviewed. Thirty studies on meropenem, imipenem, doripenem, linezolid, and vancomycin were included in the final descriptive summaries. In studies recruiting hospitalised patients, inconsistent differences in the volume of distribution (V_d) and drug clearance (CL) of the studied antimicrobials between Asian and non-Asian patients were observed. Additionally, factors other than ethnicity, such as demographic (e.g., age) or clinical (e.g., sepsis) factors, were suggested to better characterise these pharmacokinetic differences. Inconsistent differences in pharmacokinetic parameters between Asian and non-Asian subjects/patients may suggest that ethnicity is not an important predictor to characterise interindividual pharmacokinetic differences between meropenem, imipenem, doripenem, linezolid, and vancomycin. Therefore, the dosing regimens of these antimicrobials should be adjusted according to patients' demographic or clinical characteristics that can better describe pharmacokinetic differences.

External Evaluation of Population Pharmacokinetic Models for Precision Dosing: Current State and Knowledge Gaps

Predicting drug exposures using population pharmacokinetic models through Bayesian forecasting software can improve individual pharmacokinetic/pharmacodynamic target attainment. However, selecting the most adapted model to be used is challenging due to the lack of guidance on how to design and interpret external evaluation studies. The confusion around the choice of statistical metrics and acceptability criteria emphasises the need for further research to fill this methodological gap as there is an urgent need for the development of standards and guidelines for external evaluation studies. Herein we discuss the scientific challenges faced by pharmacometric researchers and opportunities for future research with a focus on antibiotics.

How to report drug concentrations or classic pharmacokinetics in regional anesthesia and pain medicine: what information needs to be provided?

When reporting individual drug concentrations or proper pharmacokinetic data, it is important to adequately report the circumstances associated with sampling, storing, analysis methodology and pharmacokinetic modelling. If this is not done in sufficient detail it will be impossible to properly evaluate the validity of the results. The present text represents a suggested approach on what to report when you are contemplating to submit a manuscript to regional anesthesia and pain medicine, this to achieve relevant standards in this context.

Parametric population pharmacokinetics of isoniazid: a systematic review

INTRODUCTION

Isoniazid (INH) plays an important role in prevention and treatment of tuberculosis (TB). However, large pharmacokinetic (PK) variations are observed in patients receiving standard INH dosages. Considering the influence of PK variations on INH efficacy or adverse reactions, we reviewed the population PK studies of INH and explored significant covariates that influence INH PK.

METHODS

The PubMed and Embase databases were systematically searched from their inception to 30 January 2023. PPK studies on INH using a parametric nonlinear mixed-effect approach were included in this review. The characteristics and identified significant covariates of the included studies were summarized.

RESULTS

Twenty-one studies conducted in adults, and seven in pediatrics were included. A two-compartment model with first-order absorption and elimination was the frequently used structural model for INH. NAT2 genotype, body size, and age were identified as significant covariates affecting INH PK variation. The median clearance (CL) value in the fast metabolizers was 2.55-fold higher than that in the slow metabolizers. Infants and children had higher CL per weight values than adults with the same metabolic phenotype. In pediatric patients, CL value increased with postnatal age.

CONCLUSIONS

Compared with slow metabolizers, the daily dose of INH should be increased by 200-600 mg in fast metabolizers. To achieve effective treatment, pediatric patients need a higher dose per kilogram than adults. Further PPK studies of anti-tuberculosis drugs are needed to comprehensively understand the covariates that affect their PK characteristics and to achieve accurate dose adjustments.