Profile analysis for assessing in vitro bioequivalence.

For locally acting drug products such as nasal aerosols and nasal sprays, therapeutic equivalence between two drug products may be established by in vitro bioequivalence studies based on measurements intended to reflect the rate and extent to which the active ingredient becomes available at the site of action. For cascade impaction or multistage liquid impinger for particle size distribution, profile analysis is required. However, we find that the analysis procedure described in the 1999 FDA guidance lacks statistical justification. In this article, we explain why FDA's approach is incorrect and propose a correct statistical method for profile analysis using the basic ideas in the FDA guidance.