Often, the short-term clinical trials, which also often involve only small numbers of 'healthy' patients don't uncover the worst side-effects, which then only emerge when a drug is taken by the public at large. Sometimes patients even die before a drug is withdrawn, as happened with Lotronex (alosetron), a drug to treat irritable bowel syndrome (IBS) in women. Lotronex had a shelf life of just nine months before it was withdrawn from the market.
The drug was approved for use in America by the drug regulator, the Food and Drug Administration (FDA), on the basis of two 12-week trials that involved 1273 women. Overall, the drug was found to be far more effective than a placebo (sugar pill).
However, researchers had noted that four cases of colitis were reported during the trials, but each case was short-lasting, mild and reversible once the drug treatment was stopped.
But soon after the drug was approved in February 2000, the FDA started receiving reports of more serious reactions of intestinal damage and ruptured bowels. The first cases were received within weeks of the approval being granted and, by November, the FDA had 70 cases of serious adverse events, including three deaths.
It's interesting to note that even faced with this overwhelming evidence, the FDA did not withdraw the drug's licence. The drug's manufacturer, however, decided to withdraw the drug from the market as the possibility of lawsuits started to loom.