Hierarchy of Clinical Trials PHASE ONE Tests a new drug's safety in the human body. A small number of healthy volunteers are usually paid to participate. PHASE TWO Tests for efficacy in several hundred patients. There can be two groups, one of which receives the standard treatment or a placebo. PHASE THREE Studies of as many as several thousand patients. This is the last step before a pharmaceutical company can request FDA approval. POST-MARKETING These trials come after FDA approval. They compare the drug with other drugs, monitor effectiveness, or see if it works on other illnesses. Return to main story

Updated Apr. 30, 1998 by bwwebmaster
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