Optimal adaptive sequential designs for crossover bioequivalence studies.

Area of Science:

• Pharmacokinetics and Drug Development
• Biostatistics
• Clinical Trial Design

Background:

• Adaptive sequential designs offer flexibility in bioequivalence studies.
• Previous work established the feasibility of such designs for crossover trials.

Purpose of the Study:

• To optimize adaptive sequential designs for crossover bioequivalence studies.
• To evaluate designs across various geometric mean ratios (GMRs) and intra-subject variation levels.
• To incorporate futility rules and study size limits into adaptive designs.

Main Methods:

• Optimization of adaptive sequential designs for bioequivalence.
• Evaluation across GMRs (70-143%) and intra-subject coefficients of variation (10-30%, 30-55%).
• Inclusion of futility stopping rules and maximum study size constraints.

Main Results:

• Optimized designs demonstrated superior performance characteristics.
• Type I error was not unduly inflated, and power remained at or above 80%.
• Average sample sizes were comparable to or smaller than conventional single-stage designs.

Conclusions:

• Optimized adaptive sequential designs provide an efficient approach for crossover bioequivalence studies.
• These designs balance statistical rigor with reduced sample size requirements.
• The inclusion of futility and size limits enhances practical application.