The Kefauver-Harris Amendment of 1962 first established which important requirement?

The Kefauver-Harris Amendment of 1962 primarily established the efficacy requirement for drugs approved for marketing in the United States. This amendment was a significant shift in drug regulation, as it mandated that not only must drugs be proven safe, but they also had to demonstrate their effectiveness for the intended use before they could be approved by the FDA.

This requirement arose in response to public health concerns following the thalidomide tragedy, where a drug that was presumed safe had drastic, negative effects due to lack of evidence verifying its effectiveness. Thus, the Kefauver-Harris Amendment aimed to ensure that pharmaceutical companies provided adequate evidence of efficacy through well-controlled clinical trials, thus protecting patients from ineffective treatments.

While the other options mention important aspects of drug regulation, such as labeling and manufacturing requirements, the unique landmark of the Kefauver-Harris Amendment was its focus on demonstrating efficacy, which was a new addition to the existing safety evaluation process.