Different phases I-IV of a clinical trial
Clinical Trials/Studies in Humans The clinical testing (investigation) of experimental drugs (previously unproven in humans, therefore "experimental") in humans is normally done in three phases (Phase I, II and III) with more and more people included in each subsequent phase. Before moving to the next phase of development the data are carefully analyzed to ensure the experimental drug is at least safe and well tolerated. After successful completion of Phase I-III testing, a company will submit the results of all of the studies to the FDA or TPD to obtain a New Drug Approval (NDA). Once the FDA or TPD grants a company with a NDA, the company can market the drug (medication) to the public. Additional testing (post-marketing or late phase III/phase IV) to look at the ongoing-term safety continues. Phase I Studies Phase I studies are primarily concerned with the drug's safety, and are the first time the drug is tested in humans. These studies are typically done in a ...