What amendment mandated that OTC products must have "adequate directions for use" on their labels?

The statement regarding the requirement for over-the-counter (OTC) products to have "adequate directions for use" on their labels is correct as it pertains to the Durham-Humphrey Amendment of 1951. This amendment distinguished between prescription and non-prescription drugs, allowing for greater clarity in labeling. It emphasized the need for OTC medications to be labeled in a way that consumers can understand how to safely and effectively use them without the guidance of a healthcare provider. This ensures that consumers have the necessary information to use the products safely, which is a key public health consideration.

On the other hand, the Kefauver-Harris Amendment of 1962 focused on the effectiveness of drugs and greater control over drug advertising and marketing; it was not specific to labeling requirements for OTC products. The Orphan Drug Act of 1983 relates to the development of medications for rare diseases and does not address OTC labeling. Similarly, the Prescription Drug Marketing Act of 1987 deals with the distribution and advertising of prescription drugs rather than OTC labeling requirements. Therefore, the Durham-Humphrey Amendment is the correct choice regarding the requirement for adequate directions on OTC product labels.