Since 1992, the US Food and Drug Administration (FDA) has offered an accelerated approval process designed to make available new drugs to treat dire conditions that lack alternative therapies. To achieve speed, the FDA allows approval based on a lower standard than required for the regular approval process. That laxity in initial oversight is supposed to be followed by rigorous postmarketing studies that validate the efficacy and safety of the drug.
Mitka M. Oversight of Fast-Track Drug Approval by FDA Stuck in Low Gear, Critics Say. JAMA. 2010;304(16):1773-1775. doi:10.1001/jama.2010.1486