Phase 3 Clinical Studies
Phase 3 studies are expanded controlled and uncontrolled trials.
They are performed after preliminary evidence suggesting
effectiveness of the drug has been obtained in Phase 2, and are
intended to gather the additional information about effectiveness
and safety that is needed to evaluate the overall benefit-risk
relationship of the drug. Phase 3 studies also provide an
adequate basis for extrapolating the results to the general
population and transmitting that information in the physician
labeling. Phase 3 studies usually include several hundred to
several thousand people.
In both Phase 2 and 3, CDER can impose a clinical hold if a study is unsafe (as in Phase 1), or if the protocol is clearly deficient in design in meeting its stated objectives. Great care is taken to ensure that this determination is not made in isolation, but reflects current scientific knowledge, agency experience with the design of clinical trials, and experience with the class of drugs under investigation.