Transdermal delivery systems are combination products composed of multiple layers of polymer films designed to deliver a drug through the skin.  Due to the complexity of design and the unique dosing regimen, evaluating extractables and leachables from a transdermal delivery system can be challenging.   A draft guidance has been issued by the FDA that covers the E&L for transdermal and topical delivery systems . The experimental approach presented in this white paper represents a rational experimental approach to E&L testing of transdermal delivery systems that will satisfy FDA expectations.

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