Phases of Clinical Trials
Phase I
These are clinical trials that are designed to evaluate the tolerated doses of new drugs or treatments and their side effects. Phase I trials usually enroll small numbers of participants.
Phase II
These trials are designed after the phase I trials and involve larger numbers of participants. Phase II trials help to detect a drug’s effectiveness and to further evaluate its safety.
Phase III
Phase III trials are undertaken with large numbers of patients. These trials compare a new therapy with the established treatment to help determine the overall efficacy of a new treatment.
Phase IV
These trials are post-marketing studies that help to gather further information regarding a drug’s side effects, tolerability and risks.