Population pharmacokinetics of a posaconazole tablet formulation in transplant adult allogeneic stem cell recipients

Dosing of IV posaconazole to treat critically ill patients with invasive pulmonary aspergillosis: a population pharmacokinetics modelling and simulation study

BACKGROUND

Posaconazole is used for the prophylaxis and treatment of invasive fungal infections in critically ill patients. Standard dosing was shown to result in adequate attainment of the prophylaxis Cmin target (0.7 mg/L) but not of the treatment Cmin target (1.0 mg/L).

OBJECTIVES

To provide an optimized posaconazole dosing regimen for IV treatment of patients with invasive pulmonary aspergillosis in the ICU.

METHODS

A population pharmacokinetics (popPK) model was developed using data from the POSA-FLU PK substudy (NCT03378479). Monte Carlo simulations were performed to assess treatment Cmin and AUC0-24 PTA. PTA ≥90% was deemed clinically acceptable. PopPK modelling and simulation were performed using NONMEM 7.5.

RESULTS

Thirty-one patients with intensive PK sampling were included in the PK substudy, contributing 532 posaconazole plasma concentrations. The popPK of IV posaconazole was best described by a two-compartment model with linear elimination. Interindividual variability was estimated on clearance and volume of distribution in central and peripheral compartments. Posaconazole peripheral volume of distribution increased with bodyweight. An optimized loading regimen of 300 mg q12h and 300 mg q8h in the first two treatment days achieved acceptable PTA by Day 3 in patients <100 kg and ≥100 kg, respectively. A maintenance regimen of 400 mg q24h ensured ≥90% Cmin PTA, whereas the standard 300 mg q24h was sufficient to achieve the AUC0-24 target throughout 14 days, irrespective of bodyweight.

CONCLUSIONS

We have defined a convenient, optimized IV posaconazole dosing regimen that was predicted to attain the treatment target in critically ill patients with invasive aspergillosis.

Personalized Antifungal Therapy Through Model-Informed Precision Dosing of Posaconazole

BACKGROUND AND OBJECTIVE

Posaconazole is a pharmacotherapeutic pillar for prophylaxis and treatment of invasive fungal diseases. Dose individualization is of utmost importance as achieving adequate antifungal exposure is associated with improved outcome. This study aimed to select and evaluate a model-informed precision dosing strategy for posaconazole.

METHODS

Available population pharmacokinetic models for posaconazole administered as a solid oral tablet were extracted from the literature and evaluated using data from a previously published prospective study combined with data collected during routine clinical practice. External evaluation and selection of the most accurate and precise model was based on graphical goodness-of-fit and predictive performance. Measures for bias and imprecision included mean percentage error (MPE) and normalized relative root mean squared error (NRMSE), respectively. Subsequently, the best-performing model was evaluated for its a posteriori fit-for-purpose and its suitability in a limited sampling strategy.

RESULTS

Seven posaconazole models were evaluated using 764 posaconazole plasma concentrations from 143 patients. Multiple models showed adequate predictive performance illustrated by acceptable goodness-of-fit and MPE and NRMSE below ± 10% and ± 25%, respectively. In the fit-for-purpose analysis, the selected model showed adequate a posteriori predictive performance. Bias and imprecision were lowest in the presence of two prior measurements. Additionally, this model showed to be useful in a limited sampling strategy as it adequately predicted total posaconazole exposure from one (non-)trough concentration.

CONCLUSION

We validated an MIPD strategy for posaconazole for its fit-for-purpose. Thereby, this study is an important first step towards MIPD-supported posaconazole dosage optimization with the goal to improve antifungal treatment in clinical practice.

Population Pharmacokinetic Modeling of Posaconazole in Japanese Patients Receiving Fungal Prophylaxis

BACKGROUND

Posaconazole is a vital drug to treat and prevent invasive fungal infections. Several factors, such as sex, body weight, total serum proteins, dietary intake, and severe mucositis, affect posaconazole pharmacokinetics (PKs). However, the relevance of other factors that affect the PKs of posaconazole in hematopoietic stem cell transplantation (HSCT) is unknown. This study explored factors influencing the PKs of posaconazole in HSCT recipients and nontransplant patients with hematological diseases.

METHODS

The authors conducted a single-institution, retrospective study. Forty-two Japanese inpatients receiving oral posaconazole tablets as prophylaxis for fungal infections were enrolled in this study. A one-compartment model with first-order absorption was used as the structural pharmacokinetic model. A population PK (PopPK) analysis was performed using a nonlinear mixed-effects modeling program, using a first-order conditional estimation method with interactions. Perl-speaks-NONMEM and R were used to evaluate the goodness of fit and visualize the output.

RESULTS

In 29% of the enrolled patients, the serum concentration of posaconazole was <0.5 mcg/mL, considered the effective range. PopPK analysis revealed that the patient had undergone HSCT within 1 year, diarrhea occurred more than 5 times a day, and aspartate aminotransferase were covariates that influenced apparent clearance (CL/F). The CL/F of posaconazole was 1.43-fold higher after HSCT and 1.26-fold higher during diarrhea.

CONCLUSIONS

PopPK analysis revealed that HSCT, diarrhea, and aspartate aminotransferase were factors associated with the CL/F of posaconazole. The trough concentration of posaconazole may be below the therapeutic range in a few patients with diarrhea and/or after HSCT. As invasive fungal infections in patients with hematologic diseases can be life-threatening, therapeutic drug monitoring of posaconazole is strongly recommended, and patients should be carefully monitored.

Factors Influencing Serum Posaconazole Concentrations in Patients with Hematologic Malignancies Receiving Delayed-Release Tablets

BACKGROUND

Posaconazole (PCZ) plays a crucial role in the prophylaxis and treatment of invasive fungal infections in hematologic malignancies. PCZ concentrations reportedly vary among patients receiving delayed-release tablets (DRT). However, the factors influencing these concentrations remain insufficiently elucidated. Therefore, this study aimed to evaluate the factors influencing PCZ concentrations and their effect on the probability of target attainment (PTA) using a population pharmacokinetic (PPK) approach. We also explored the relationship between PCZ exposure and hepatotoxicity.

METHODS

This retrospective study included adult patients with hematologic malignancies who received PCZ DRT. A PPK model was developed based on observational data for 130 concentrations in 28 patients. Simulation analyses were performed to assess the PTA at standard doses of 0.7 and 1.0 mg/L for prophylaxis and treatment, respectively. Estimated concentrations were used to evaluate the correlation between PCZ exposure and hepatotoxicity.

RESULTS

Significant factors influencing PCZ concentrations included body weight, serum total protein levels, and diarrhea. Diarrhea correlated with decreased PCZ concentrations resulting in up to 26% lower PTA compared with that without diarrhea. Moreover, PTA declined markedly as the total protein levels decreased from 6.6 g/dL to 4.4 g/dL. The incidence of hepatotoxicity was 17.4% (4/23); no significant relationship could be established between the PCZ concentrations and hepatotoxicity (P = 0.188).

CONCLUSIONS

We identified the factors affecting PCZ exposure, which could not be detected by PPK analysis using data from clinical trials. Our results suggest that the generally recommended dose of PCZ causes underexposure in patients with hematologic malignancies characterized by high body weight, hypoproteinemia, or concurrent diarrhea. Therapeutic drug monitoring for DRT may be recommended, especially in patients with these risk factors.

Model Based Estimation of Posaconazole Tablet and Suspension Bioavailability in Hospitalized Children Using Real-World Therapeutic Drug Monitoring Data in Patients Receiving Intravenous and Oral Dosing

Invasive fungal infections are a major cause of morbidity and mortality for immunocompromised patients. Posaconazole is approved for treatment and prophylaxis of invasive fungal infection in adult patients, with intravenous, oral suspension, and gastroresistant/delayed-released tablet formulations available. In Europe, until very recently, posaconazole was used off-label in children, although a new delayed-release suspension approved for pediatric use is expected to become available soon. A population pharmacokinetic model was developed which uses posaconazole therapeutic drug monitoring data following intravenous and oral dosing in hospitalized children, thus enabling estimation of pediatric suspension and tablet oral bioavailability. In total, 297 therapeutic drug monitoring plasma levels from 104 children were included in this analysis. The final model was a one-compartment model with first-order absorption and nonlinear elimination. Allometric scaling on clearance and volume of distribution was included a priori. Tablet bioavailability was estimated to be 66%. Suspension bioavailability was estimated to decrease with increasing doses, ranging from 3.8% to 32.2% in this study population. Additionally, concomitant use of proton pump-inhibitors was detected as a significant covariate, reducing suspension bioavailability by 41.0%. This is the first population pharmacokinetic study to model posaconazole data from hospitalized children following intravenous, tablet, and suspension dosing simultaneously. The incorporation of saturable posaconazole clearance into the model has been key to the credible joint estimation of tablet and suspension bioavailability. To aid rational posaconazole dosing in children, this model was used alongside published pharmacodynamic targets to predict the probability of target attainment using typical pediatric dosing regimen.

An Integrated Population Pharmacokinetic Analysis for Posaconazole Oral Suspension, Delayed-Release Tablet, and Intravenous Infusion in Healthy Volunteers

BACKGROUND

Posaconazole is widely used for the prophylaxis and treatment of invasive fungal diseases. Because of the limited and variable absorption of the initially available oral suspension, a delayed-release tablet and intravenous formulation were developed.

OBJECTIVE

This study aimed to characterize the pharmacokinetics, including the absolute oral bioavailability, of all posaconazole formulations in healthy volunteers.

METHODS

Data from 182 healthy volunteers with 3898 densely sampled posaconazole concentrations were pooled from eight phase I clinical studies on the three formulations of various single and multiple dosage regimens between 50 and 400 mg. Analysis and simulations were performed using NONMEM 7.5.0. In the covariate analysis, the influence of food (fed vs fasted), nonlinearity, and for the delayed-release tablet, comedication (antacid, ranitidine, esomeprazole, and metoclopramide) were tested.

RESULTS

A two-compartment model with respectively, four and eight absorption transit compartments, best described the profiles of the oral suspension and delayed-release tablet. For the suspension, both a food effect and a dose-dependent nonlinear bioavailability were quantified, resulting in lower bioavailability when fasted or at a higher dose. The typical bioavailability of the suspension at 100 mg and 400 mg was derived to be respectively, 17.1% and 10.1% under fasted conditions and 59.1% and 49.2% under fed conditions. The absolute bioavailability of the delayed-release tablet was 58.8% (95% confidence interval 33.2-80.4) under fasted conditions and approached complete absorption under fed conditions for dosages up to 300 mg. Food intake reduced the absorption rate constant of the suspension by 52.2% (confidence interval 45.2-59.2). The impact of comedication on the absorption of the delayed-release tablet was not statistically significant. Model-based simulations indicate that under fed conditions, the licensed dosages of the three formulations yield a steady-state trough concentration ≥ 0.7 mg/L in over 90% of healthy volunteers. About 35% of healthy volunteers who receive the licensed 300-mg delayed-release tablet under fasted conditions do not achieve this target, while for the suspension this percentage varies between 55 and 85%, depending on the dose.

CONCLUSIONS

For both oral posaconazole formulations, we quantified bioavailability and absorption rate, including food effects, in healthy volunteers. The pharmacokinetic superiority of the delayed-release tablet was demonstrated under both fed and fasted conditions, compared with the oral suspension. The impact of food on the bioavailability of the delayed-release tablet was larger than anticipated, suggesting that administering the delayed-release tablet with food enhances absorption.

Progress of triazole antifungal agent posaconazole in individualized therapy

WHAT IS KNOWN AND OBJECTIVE

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

METHODS

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

RESULTS AND DISCUSSION

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

WHAT IS NEW AND CONCLUSION

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

A Review of Population Pharmacokinetic Models of Posaconazole

Posaconazole is often used for the prophylaxis and treatment of invasive fungal infections (IFI). However, intra- and inter-individual differences and drug interactions affect the efficacy and safety of posaconazole. Precision dosing of posaconazole based on the population pharmacokinetic (PopPK) model may assist in making significant clinical decisions. This review aimed to comprehensively summarize the published PopPK models of posaconazole and analyze covariates that significantly influence posaconazole exposure. Articles published until May 2022 for PopPK analysis of posaconazole were searched in PubMed and EMBASE databases. Demographic characteristics, model characteristics, and results of PopPK analysis were extracted from the selected articles. In addition, the steady-state pharmacokinetic profiles of posaconazole were simulated at different covariate levels and dosing regimens. Out of the 13 studies included in our review, nine studies included adults, three included children, and one included both adults and children. All oral administration models were one-compartment models, and all intravenous administration models were two-compartment models. Body weight, proton pump inhibitors, and incidence of diarrhea were found to be important covariates. Clinically, the potential impact of factors such as patient physiopathologic characteristics and comorbid medications on posaconazole pharmacokinetics should be considered. Dose adjustment in combination with TDM or replacement with a tablet or intravenous formulation with higher exposure may be an effective way to ensure drug efficacy as well as to reduce fungal resistance. Meanwhile, published models require further external evaluation to examine extrapolation.

External evaluation of published population pharmacokinetic models of posaconazole

Population pharmacokinetic (PopPK) models of posaconazole have been established to promote the precision dosing. However, the performance of these models extrapolated to other centers has not been evaluated. This study aimed to conduct an external evaluation of published posaconazole PopPK models to evaluate their predictive performance. Posaconazole PopPK models screened from the PubMed and MEDLINE databases were evaluated using an external dataset of 213 trough concentration samples collected from 97 patients. Their predictive performance was evaluated by prediction-based diagnosis (prediction error), simulation-based diagnosis (visual predictive check), and Bayesian forecasting. In addition, external cohorts with and without proton pump inhibitor were used to evaluate the models respectively. Ten models suitable for the external dataset were finally included into the study. In prediction-based diagnostics, none of the models met pre-determined criteria for predictive indexes. Only M4, M6, and M10 demonstrated favorable simulations in visual predictive check. The prediction performance of M5, M7, M8, and M9 evaluated using the cohort without proton pump inhibitor showed a significant improvement compared to that evaluated using the whole cohort. Consistent with our expectations, Bayesian forecasting significantly improved the predictive per-formance of the models with two or three prior observations. In general, the applicability of these published posaconazole PopPK models extrapolated to our center was unsatisfactory. Prospective studies combined with therapeutic drug monitoring are needed to establish a PopPK model for posaconazole in the Chinese population to promote individualized dosing.