The use of healthy volunteers to document the rate of absorption and excretion from the body of a compound's active ingredients . Companies conduct bioavailability studies both at the beginning of human testing and just prior to marketing to show that the formulation used to demonstrate safety and efficacy in clinical trials is equivalent to the product that will be distributed for sale. During the review period, the FDA may ask the company for additional information about the product or seek clarification of the data contained in the application . Postapproval Research - Experimental studies and surveillance activities undertaken after a drug is approved for marketing . Regulatory authorities can require companies to conduct Phase IV studies as a condition of market approval.
Companies often conduct post-marketing studies in the absence of a regulatory mandate.
Congress of the United States, Office of Technology Assessment.