Which amendment was the first to require that pharmaceutical manufacturers prove the efficacy of prescription drugs before marketing?

The Kefauver-Harris Amendment of 1962 is recognized as the first significant legislation that mandated pharmaceutical manufacturers to prove the efficacy, as well as the safety, of their prescription drugs prior to marketing them. Prior to this amendment, the Food, Drug, and Cosmetic Act of 1938 had established basic safety requirements for drugs, but it did not specifically require evidence of efficacy.

The Kefauver-Harris Amendment arose in response to the Thalidomide tragedy, during which a drug led to severe birth defects when used by pregnant women. This highlighted the need for stricter regulations regarding drug approval processes. As a result, this amendment established a more rigorous standard by requiring companies to conduct clinical trials demonstrating that their drugs were effective for their intended uses.

In summary, the Kefauver-Harris Amendment was pivotal in shifting the landscape of drug approval by emphasizing the importance of demonstrating efficacy in addition to safety, which shaped how prescription drugs are evaluated and approved up to the present day.