On May 22, 2018, the US Food and Drug Administration (FDA) issued draft guidance for drug makers on maximal usage trials for the purpose of adding a topical active ingredient to an over-the-counter (OTC) drug monograph.
A maximal usage trial is a pharmacokinetic (PK) trial designed to maximize the potential for topical drug absorption to occur. Maximal usage trials also determine the in vivobioavailability of topical drugs to help FDA understand “the potential for systematic exposure to topically applied active ingredients,” reported RAPS.1
FDA stated that “such information can help inform an FDA determination of whether additional safety data are needed to support a finding that an OTC drug containing that active ingredient is generally recognized as safe and effective (GRASE) for its intended use.”
Maximal usage trials are also recommended for sponsors developing topical drugs under a new drug application (NDA). “Before including an active ingredient in an OTC monograph, it is important to evaluate the absorption of a representative range of formulations,” FDA writes.
FDA released the draft guidance after receiving industry comments following the guidance on demonstrating safety and effectiveness for non-prescription sunscreen products.
The newly issued draft guidance includes more than just guidance on sunscreen ingredients and provides recommendations for other topically applied drugs. In the near future, FDA may establish circumstances for an active ingredient to be advertised under an OTC monograph.