Today FDA announced finalizations in two guidance documents for transdermal systems (TDS) one relative to skin adhesion studies (here)  and one related to skin irritation and sensitization studies (here).  The revisions to the previous drafts came after FDA considered a number of industry comments to those drafts. With the finalization of the guidance documents, FDA also updated 23 bioequivalence (BE) guidance documents for TDS products and issued 2 new guidances.  The revised and new BE guidances address bioequivalence studies required for the individual product as well as adhesion and irritation and sensitization studies necessary to support bioequivalence.

It is essential for sponsors to understand the current recommendations in these two new guidances when preparing to test for these critical attributes in future submissions.  The question of whether companies with ending applications will be required to conform to these new final guidances or whether sponsors of approved applications will be required to repeat these studies if there are reports of problems seen post marketing. It is important to note that these two final guidance documents apply strictly to ANDAs.