What happens during the phase 2 study of a clinical trial?
Once a drug has been shown to be safe, it must be tested for efficacy. This second phase of testing may last from several months to 2 years and involve up to several hundred patients. Most phase 2 studies are randomized trials: one group of patients receives the experimental drug while a second “control” group receives a standard treatment or placebo. Often, these studies are “blinded,” which means that neither the patients nor the researchers know the identities of those getting the experimental drug. This way, the study can provide the pharmaceutical company and the FDA with comparative information about the relative safety of the new drug and its effectiveness. Only about one-third of experimental drugs successfully complete both phase 1 and phase 2 studies.
