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# Transdermal Irritation/Sensitization Assessment
- URL: https://www.fdaweb.com/transdermal-irritation-sensitization-assessment/
- Published: 2023-04-12T12:00:00.000Z
- Updated: 2026-09-14T18:25:10.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5154201

FDA has published a draft guidance, *Assessing the Irritation and Sensitization Potential of Generic Transdermal and Topical Delivery Systems for ANDAs*, with recommendations for the design and conduct of studies to evaluate the *in vivo* skin irritation and sensitization (I/S) potential of a proposed drug transdermal or topical delivery system (TDS). The [document](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/assessing-irritation-and-sensitization-potential-transdermal-and-topical-delivery-systems-andas?utm%5Fmedium=email&utm%5Fsource=govdelivery) says its recommendations relate to studies submitted in support of an ANDA. It revises a 10/2018 guidance with the same name to **(1)** clarify recommendations for the design and conduct of studies to evaluate the *in vivo* skin I/S potential of a proposed TDS; **(2)** clarify when an *in vivo* study to assess the sensitization potential of a TDS product may not be needed; and **(3)** provide guidance to applicants intending to use alternative scoring scales or alternative approaches to compare I/S between the test and reference TDS.

The agency also issued a [draft guidance](http://fdaweb.com/login.php?sa=v&aid=D5154196&cate=&stid=%241%243p5.Om..%241SU454pj1p3s53Y5lBwtF.&ref=fdaweb.com) on assessing adhesion with TDS for ANDAs. It says the two drafts were published to provide clear, convenient information to current and potential ANDA applicants as outlined in the agency’s [Drug Competition Action Plan](https://www.fda.gov/drugs/guidance-compliance-regulatory-information/fda-drug-competition-action-plan?utm%5Fmedium=email&utm%5Fsource=govdelivery).