Time was when the Food and Drug Administration would give a new drug the go-ahead for marketing based on a handful of studies involving no more than a few thousand patients. Then millions of prescriptions would be written over the next few years, and the drug would finally have its real test of safety on the open market, with the American consumer as the guinea pig. If the drug flunked the real-world test, it would be taken off the market, with a flurry of product liability lawsuits and calls for regulatory reform. This script is familiar from fen-Phen to Vioxx.