FDA releases new guidances on adhesive performance and skin irritation studies for transdermal generic drugs

The U.S. Food and Drug Administration has issued two new guidances that address transdermal or topical delivery systems for generic drugs. One is a final guidance that outlines how to assess adhesive performance in these products, and the other is a draft guidance that describes in‑vivo methods for evaluating skin irritation.

The guidances aim to give manufacturers clearer expectations for testing and documentation, helping them demonstrate that their transdermal products meet safety and efficacy standards. By standardizing the approach to adhesive and irritation assessments, the FDA hopes to streamline the review of generic applications.

The announcements come alongside a proposed amendment to 21 CFR Part 207 that would allow distributed manufacturers to register as a single establishment. This change could shift industry focus toward maintaining product consistency across multiple sites, reflecting a broader move toward ecosystem‑centric assurance in manufacturing.