1. Maximal usage trials for topically applied active ingredients being considered for inclusion in an over-the -counter monograph: study elements and considerations Publication: Silver Spring, MD : Center for Drug Evaluation and Research, May 2019 Subject(s): Administration, TopicalDrug ApprovalNonprescription DrugsAbsorption, PhysiologicalClinical Trials as TopicSafetyHumansUnited StatesUnited States. Department of Health and Human Services.United States. Food and Drug Administration.