Deeming a drug safe is much easier than deeming it effective.
One thing most people don’t understand is that the hard scientific costs of drug development at a scientific level are usually millions of dollars, not billions.
What happened in the late 50’s and 60’s was the birth of children with limb malformities/malformations as a side effect of using Thalidiomide, a cancer drug. It was a huge problem.
The thalidiomide crisis exploded into a blowback style reaction that would inflate the cost of drug development to Billions of dollars and make patent lawyers rich.
This was a dumb move and the result of a scientifically inept congress, which for the most part we still have.
The Kefauver Harris act is on the same level as the 1984 SCPA (Semiconductor Chip Protection Act) for the pharma industry.
It was passed in 1962 as an amendment to the FDA. It required proof of efficacy in addition to safety for approval of new drugs. What happened with thalidomide was a proof of safety issue and had very little to do with efficacy.
Prior to Kefauver Harris act: 7 months for filing for an investigational drug. Now: 7 years or more.