Bioequivalence for Topical Drug Products

Abstract

This chapter discusses the current approaches for bioequivalence (BE) assessment of generic topical drug products by the United States Food and Drug Administration (US FDA). The approval of these drug products are governed by guidances and federal regulations that facilitate the development and subsequent approval of bioequivalent topical drug products. The goal is for these generic topical drug products to be therapeutically equivalent to the innovator (reference) product. The variation in the site of activity, multiple dosage forms (vehicles), and therapeutic drug classes are all critical factors in the determination of appropriate scientific/clinical approaches that are most suitable to demonstrate BE between the generic and reference product. The most common type of topical drug products is considered to be locally acting dermatologic drug products. So, establishing BE has been a daunting task due to the site of action commonly being in or on the skin. In most cases, BE studies with clinical endpoints are recommended for topical drug products, except for in the case of topical dermatologic corticosteroids in which in vivo pharmacodynamic studies are recommended. Despite these limitations, the US FDA is forging ahead through regulatory science initiatives and collaborative research projects to explore the progression of new in vitro and/or in vivo methods; along with improvement of the current approaches used for BE assessment of generic topical drug products.