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# Post-market Safety Issues Not Obvious in Review: Study
- URL: https://www.fdaweb.com/post-market-safety-issues-not-obvious-in-review-study/
- Published: 2017-03-30T12:00:00.000Z
- Updated: 2026-09-14T22:15:00.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5138334

FDA researchers say that although drugs approved with a Boxed Warning or priority review are more likely to experience post-marketing safety events, other information provided during the FDA drug review that is easy to quantify is generally not associated with such post-marketing events. “It appears that these post-marketing events are not discernible during a pre-marketing review and therefore might not be avoidable using current review data,” the researchers [write](https://link.springer.com/article/10.1007%2Fs40264-017-0526-1?ref=fdaweb.com) in the journal *Drug Safety*.

The study used an internal agency database listing every new small molecule drug submitted to CDER on or after 11/21/97 and approved and commercially launched before 12/31/09\. The researchers looked at 219 new molecular entities for post-marketing Boxed Warnings or withdrawal from the market due to safety concerns. In the sample, 30 received Boxed Warnings by 7/31/16 and 11 were withdrawn for safety reasons.

“Contrary to prevailing hypotheses, we find that neither clinical trial sample sizes nor review time windows are associated with the addition of a post-marketing Boxed Warning or safety withdrawal,” the authors write. “However, we do find that new drugs approved with either a Boxed Warning or priority review are more likely to experience post-marketing Boxed Warnings. Furthermore, drugs approved with Boxed Warnings tend to receive post-marketing Boxed Warnings resulting from new safety information that are unrelated to the original warning. Drugs approved with a Boxed Warning are 3.88 times more likely to receive a post-marketing Boxed Warning, while drugs approved with a priority review are 3.51 times more likely to receive a post-marketing Boxed Warning.”