Bioequivalence for topical products--an update.

With the exception of topical glucocorticoids, demonstrating bioequivalence between generic and reference topical products entails conducting clinical end-point trials which are both lengthy and expensive. Considerable effort has been channeled towards development and validation of alternative approaches to demonstrate bioequivalence of topical and transdermal products. The critical opportunity pathways identified by the FDA for the industry for topical bioequivalence include the following surrogate methods: in vitro studies, dermatopharmacokinetic method, dermal microdialysis and near infrared spectroscopy. This review provides an update of recent advances in these methodologies.