Dependence of Bioavailability on Mean Absorption Time: What Does It Tell Us?

Area of Science:

• Pharmacokinetics
• Drug Metabolism and Transport
• Pharmaceutical Sciences

Background:

• Bioavailability (F) and mean absorption time (MAT) are key pharmacokinetic parameters for oral drug administration.
• Previous research suggests a potential dependency between drug bioavailability and absorption rate.
• Understanding this relationship is crucial for accurate drug characterization.

Purpose of the Study:

• To investigate the relationship between oral drug bioavailability (F) and mean absorption time (MAT).
• To determine how interindividual variability in absorption rate affects drug bioavailability.
• To explore the utility of the F versus MAT plot in bioavailability study analysis.

Main Methods:

• Population analysis using nonlinear mixed-effects modeling.
• Modeling oral drug absorption using a sum of two inverse Gaussian functions to estimate F and MAT.
• Utilizing data from bioavailability studies in healthy volunteers.

Main Results:

• For trospium and ketamine, bioavailability (F) significantly decreased as mean absorption time (MAT) increased.
• For propiverine, bioavailability (F) significantly increased with increasing mean absorption time (MAT).
• Interindividual variability in F was largely explained by variability in MAT; absorption time distribution also correlated with MAT for some drugs.

Conclusions:

• The relationship between drug bioavailability (F) and mean absorption time (MAT) is drug-specific and can be influenced by factors like gastrointestinal transit or hepatic extraction.
• The F versus MAT plot serves as a valuable diagnostic tool for assessing drug bioavailability study outcomes.
• Characterizing the interplay between absorption rate and bioavailability enhances pharmacokinetic understanding.