Maximal Usage Trials Guidance for Topical OTC Drugs Finalized By FDA

The US Food and Drug Administration (FDA) finalized guidance on conducting maximal usage trials (MUsT) to support the inclusion of an active ingredient in an OTC monograph.

This guidance represents the current thinking of the Food and Drug Administration (FDA or Agency) on “Maximal Usage Trials for Topically Applied Active Ingredients Being Considered for Inclusion in an Over-The-Counter (OTC) Monograph: Study Elements and Considerations Guidance for Industry”. It does not establish any rights for any person and is not binding on FDA or the public. You can use an alternative approach if it satisfies the requirements of the applicable statutes and regulations. To discuss an alternative approach, contact the FDA office responsible for this guidance.

According to FDA, the MUsT guidance was developed in response to comments it received from industry on its draft and final guidances on demonstrating safety and effectiveness for nonprescription sunscreens that called on the agency to provide more detailed guidance on MUsTs.

This guidance provides recommendations for the conduct of in vivo absorption trials for topically applied active ingredients that are under consideration for inclusion in an OTC drug monograph. A MUsT) is a standard approach to assess the in vivo bioavailability of topical drug products intended for local therapeutic effects. The methodology described in this guidance adapts MUsT principles for active ingredients being considered for inclusion in an OTC monograph. Because information from a MUsT can help identify the potential for systemic exposure to a topically applied active ingredient, such information can help inform an FDA determination of whether additional safety data are needed to support a finding that a topical OTC drug containing that active ingredient is generally recognized as safe and effective (GRASE) for its intended use.

For More detail refer below link for guideline: