Understanding variability in posaconazole exposure using an integrated population pharmacokinetic analysis

Area of Science:

• Pharmacology
• Clinical Pharmacy
• Drug Metabolism

Background:

• Posaconazole oral suspension is a key antifungal agent, but its effectiveness is hampered by highly variable patient pharmacokinetics due to inconsistent absorption.
• Understanding factors influencing posaconazole absorption is critical for optimizing therapeutic outcomes in immunocompromised populations.

Purpose of the Study:

• To characterize the population pharmacokinetics of posaconazole in adults.
• To identify demographic, clinical, and drug-related factors affecting posaconazole pharmacokinetics and bioavailability.

Main Methods:

• A population pharmacokinetic approach using nonlinear mixed-effects modeling was applied to data from 102 participants (patients and healthy volunteers).
• A one-compartment model with first-order absorption and elimination best described the data, with investigations into factors like mucositis, diarrhea, and drug-drug interactions.

Main Results:

• Posaconazole bioavailability was 55% lower in patients compared to healthy volunteers.
• Proton pump inhibitors (PPIs), metoclopramide, mucositis, and diarrhea significantly reduced bioavailability (35-58%).
• Nutritional supplements increased bioavailability by 129%, while rifampin and phenytoin increased clearance by over 600%.

Conclusions:

• Posaconazole absorption is significantly impacted by coadministered drugs (e.g., PPIs, rifampin) and clinical conditions (e.g., mucositis, diarrhea).
• Strategies to improve posaconazole absorption include avoiding interacting medications like PPIs and metoclopramide, and administering the drug with food or nutritional supplements.