Acceptable and unacceptable procedures in bioavailability and bioequivalence trials

Area of Science:

• Pharmacology
• Drug Development
• Regulatory Science

Background:

• US FDA and EU guidelines mandate specific procedures for bioavailability and bioequivalence studies.
• Non-compliance with these guidelines can impede drug development, particularly at the New Drug Application (NDA) or Abbreviated New Drug Application (ANDA) stages.
• Common procedural errors include inappropriate analytical methods and data handling in pharmacokinetic and statistical analyses.

Purpose of the Study:

• To delineate acceptable and unacceptable procedures in conducting bioavailability and bioequivalence studies.
• To provide guidance on operating principles and pharmacokinetic considerations for regulatory submissions.
• To highlight common pitfalls in pharmacokinetic and statistical analysis that can affect study outcomes.

Main Methods:

• Review and comparison of established guidelines from regulatory bodies (e.g., FDA, EU).
• Detailed description of pharmacokinetic principles relevant to bioavailability and bioequivalence.
• Identification and explanation of commonly used, yet unacceptable, analytical procedures.

Main Results:

• Compartmental analysis is unacceptable for calculating Cmax, tmax, and AUC in pivotal studies; non-compartmental analysis is required.
• Pharmacokinetic analysis must use homogeneous concentrations, avoiding sums of parent drugs and metabolites.
• Absolute bioavailability assessment with dose-dependent kinetics necessitates consideration of plasma clearance.
• Simultaneous fitting is required for drugs and metabolites; disregarding or simulating data is unacceptable.
• The multiplicative model is preferred over the additive model for assessing bioequivalence of Cmax and AUC.

Conclusions:

• Strict adherence to recommended procedures in bioavailability and bioequivalence studies is essential for successful drug development.
• Understanding and applying correct pharmacokinetic principles and analytical methods are critical for regulatory approval.
• This paper serves as a guide to navigating acceptable practices, preventing common errors in study design and analysis.