The 1951 amendment to the FDCA addressed classification of drugs as Rx vs OTC.

• A. Regulation of cosmetics labeling
• B. Classification of drugs as Rx vs OTC
• C. Prohibition of vaccines
• D. Expansion of FDA authority to regulate devices

Answer: (B)

The main idea this item tests is the formal split in drug regulation created by the 1951 amendment, which established prescription versus over-the-counter (OTC) classifications. This amendment, known for introducing the Rx-only concept and the requirement that certain drugs be dispensed only with a physician’s prescription, clarified how drugs are categorized and labeled based on whether professional supervision is needed. It also set rules for labeling and dispensing, including the use of an Rx legend and the handling of refills for prescription drugs. This is why the answer focuses on classification of drugs as Rx vs OTC—the amendment directly created and defined that distinction. The other options point to separate regulatory areas (cosmetics labeling, vaccines, or devices) that are governed by different statutes or later amendments and are not the focus of this 1951 change.