What law, established in 1951, distinguishes between legend and OTC drugs?

The Durham-Humphrey Amendment, established in 1951, is significant because it created a clear distinction between legend drugs (prescription medications) and over-the-counter (OTC) drugs. This law recognized that certain medications require a prescription from a licensed healthcare provider due to their potential for misuse or side effects that necessitate medical supervision. Conversely, it allowed for the sale of other medications without a prescription, provided they could be safely used by the general public without the direct guidance of a healthcare professional.

This amendment addressed the necessity for patients to have access to medications that didn't require a healthcare provider’s oversight while ensuring that more controlled substances remained within the prescription-only category, thus enhancing patient safety and promoting informed use of medications.