What are the phases of clinical trials of a new drug?
Most research that involves the testing of a new drug moves ahead in a series of steps called phases. There are usually 3 phases: Phase I trials: These first studies test different ways to take a new drug, different dosages, and the side effects of the drug. A phase I trial usually enrolls only a small number of people. Phase II trials: A phase II trial continues to test the safety of a drug, and begins to evaluate how well the new drug works. Phase III trials: These studies compare a new drug with the current standard treatment. Participants are usually randomly assigned to either the group receiving the standard treatment or the group receiving the new treatment. (This is called randomization.) Phase III trials often enroll large numbers of people. They may be conducted at many doctors’ offices, clinics, and cancer centers nationwide.
