In the postmarket setting, the regulation of medicines requires an assessment of the balance between their benefits and risks and, as new information becomes available, may require regulatory actions that range from changes in the product label to withdrawal of a drug from the market. A series of unforeseen consequences of drug administration to vulnerable patients has shaped the modern history of the regulation of medications. In the 1960s, for instance, thalidomide given to pregnant women resulted in birth defects or death in several thousand of their offspring. The framework for modern drug regulation largely emerged from the development of various measures to prevent similar drug-safety disasters.