In the United States, the manufacture and sale of OTC substances are regulated by the Food and Drug Administration. The FDA requires that all "new drugs" obtain a New Drug Application (NDA) before entering interstate commerce, but the act exempts any drugs generally recognized as safe and effective (GRAS/E). To deal with the vast number of OTC drugs that were already on the market before the requirement that all drugs obtain an NDA, the FDA created the OTC monograph system to review classes of drugs and to categorize them as GRAS/E after review by expert panels. Certain classes of OTC drugs would not be required to obtain an NDA and could remain on the market if they conformed to the monograph guidelines for doses, labeling, and warnings finalized in the Code of Federal Regulations