phase I, II, III and IV studies

Different phases of clinical trials that are run to develop a new test or treatment, such as a drug. Phase I (one) involves using healthy human volunteers to check the safety of the test or treatment. In phases II–IV (two to four), patients with the disease that the researchers are interested in are given the treatment and the optimal dose is worked out. Researchers study these patients to see whether it works, how long the effects last and whether there are any adverse effects.  ^HTAI