Individual Bioequivalence—A Review of the FDA Draft Guidance

Abstract

As more generic drugs become available in the marketplace, it is a public concern whether the quality, safety, and efficacy of generic drugs are the same as the brand name drug. Under current regulation, the United States Food and Drug Administration (FDA) only requires that evidence of bioequivalence in average bioavailability be provided for assessment of bioequivalence. FDA, however, does not require that bioequivalence among generic copies of the same brand name drug be demonstrated. As a result, it is a concern whether these generic drugs can be used interchangeably. To address this question, the concepts of population bioequivalence for drug prescribability and individual bioequivalence for drug switchability have been proposed. In this paper, we provide a comprehensive review of the draft FDA guidance on “In Vivo Bioequivalence Studies Based on Population and Individual Bioequivalence Approaches” which was distributed for comment in October 1997. The discussion will be primarily on the FDA proposed criteria, design, statistical methods, and interpretations on the assessment of individual bioequivalence from the pharmaceutical industry perspective.