(RxWiki News) Even with FDA approval, the overall safety of some prescription medications may be unknown.
Researchers curious about the safety of new medicines recently examined the frequency of black-box warnings and withdrawals after market approval.
Black-box warnings, issued by the US Food and Drug Administration (FDA), are the strictest medicine label warnings due to the severity and frequency of hazardous reactions.
The researchers found that a significant number of new medications were being withdrawn from the market due to safety concerns.
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The study was led by Cassie Frank, MD, a doctor at Cambridge Health Alliance and instructor at Harvard Medical School in Boston.
Dr. Frank and team wanted to compare the frequency of black-box warnings and withdrawals pre- and post-1992, when the Prescription Drug User Free Act (PDUFA) was enacted.
PDUFA was created to speed up the approval process of medications, allowing patients to have access to more choices. With the act, approval times decreased by 52 percent to 16.1 months on average.
The team gathered a list of all NMEs the FDA approved between 1975 and 2009. NMEs are new molecular entities — ingredients in medicines never before marketed in the United States. The study showed that the FDA approved 748 NMEs during this time period. Non-steroidal anti-inflammatory drugs (NSAIDs) and antidepressants accounted for the majority of warnings and market withdrawals.
Using the Physician's Desk Reference and the FDA website, researchers were able to identify which medications were withdrawn or black-box listed in the same 35-year period.
The study authors analyzed the collected data with statistical software SAS, which created plots to demonstrate the amount of time between FDA approval and warning label or withdrawal.
The researchers found that, of the 748 approved NMEs, 32 were withdrawn for safety concerns. An additional 114 received one or more black-box warnings. Of the 32 withdrawals, half of these occurred within five years of being released. Of the 114 warnings, half of these occurred within 12 years of the medicine's release. Further testing showed that, within 25 years of approval, new medications had about a one-in-three chance of being removed or black-box labeled.
Although the researchers said they could not directly link the increase in warnings and withdrawals to PDUFA, they were still wary of the safety of newer medicines.
"By the time many drugs receive serious safety warnings, millions of Americans have already been exposed to their side effects, which can sometimes be fatal," Dr. Frank said in a press release.
This study was published August 4 in the journal Health Affairs. The authors disclosed no conflicts of interest.