According to the Government Accountability Office (GAO), the Food and Drug Administration (FDA) has allowed drugs to stay on the market even when follow-up studies found that they weren't effective. This and other practices are under review by the GAO, which investigated the FDA's "accelerated approval program."
The program is used to approve drugs for the most serious conditions and is intended to quickly make available medications that are anticipated to be effective. However, a condition of the program is that drug manufacturers conduct follow-up studies to confirm the drug's benefits.
A report from the GAO says that only 64 percent of the studies required under the program have been completed; one-third are pending; and in the 16 years that the FDA has used accelerated approval, it has never recalled a drug due to missing or unsatisfactory follow-up data.
The GAO concluded that the FDA has no official policy for pulling drugs off the market under the accelerated approval program. The FDA responded that it would be nearly impossible to create a standard policy for withdrawals, due to the unique circumstances of individual drugs.