Clinical studies are organized into specific phases, each of which addresses different research questions. Each phase builds upon the previous one, until the drug candidate is shown to be safe and effective in all studies.
- Phase 1: The first time the drug candidate is given to human volunteers. Phase 1 studies are done in a small group to evaluate how much of the medicine may be safe to take in future studies.
- Phase 2: Study doctors examine the effectiveness of the drug candidate against treating disease, as well as continue to monitor safety. These studies typically enroll 50 to 300 people.
- Phase 3: The goals of a phase 3 study are to understand whether the medicine is safe for patients to take, and to see if it is effective at treating disease. This is the most advanced study before the regulatory agencies review all the clinical data to determine if the medicine can be made available to the public by prescription, so Phase 3 studies enroll large groups of people (several hundred to several thousand, depending on the disease).
