Nevertheless, human cell culture testing has become a fundamental part of the safe production of many common drugs. FDA regulation and approval extends not just to the chemistry of a drug but also to how it is manufactured, to ensure that the delivered product is safe.

Old medicines are still evaluated for ongoing safety profiles, including interactions with new classes of drugs that may come on the market. Users of these medicines benefit from this.

As an example, here's a 2018 study on Tylenol using the HEK 293 line: https://pubmed.ncbi.nlm.nih.gov/29273526/