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What is a clinical trial

The scientific method, when applied to the search for new medicines and treatments, results in a rigorous system of preclinical, animal, and human testing (trials). Before human trials begin, the U.S. Food and Drug Administration (FDA) requires convincing evidence that the drug will not harm humans and that the likelihood of effectiveness exists. Once human trials begin, a multi-year, multiphase system of testing begins.

Clinical trials are research studies involving people like you who volunteer to help answer medical and scientific questions about new therapies and treatments in an effort to improve health and health outcomes.

There are several kinds of clinical trials:

  • Prevention trials: study ways to prevent disease in those who have never had them. They usually do not involve experimental drugs or devices.
  • Screening trials: test new ways to detect disease.
  • Treatment trials: test new medical devices and drugs, or they test new ways of using them.

Clinical trials occur in four phases.

  • Phase I studies: are "first in human" studies. Usually, after animal studies indicate that the drug or device is safe enough to test on humans, healthy adults volunteer to test whether they drug is safe and how it is metabolized and excreted by the body. Once these facts are known, the investigational article moves into Phase II.
  • Phase II studies. In these studies, people with the disease for which the drug or device is meant to help are recruited to participate in wider testing for both safety and effectiveness.
  • Phase III studies again recruit volunteers with the disease under study to participate in a wider study with more participants to further test safety and effectiveness. These usually take place at multiple sites with a larger pool of volunteers to test what the drug or device will do in a "real world" setting. Once the first three phases of study are complete, the data is presented to the FDA or other regulatory authorities to seek marketing approval for the new drug or device. After marketing approval, studies may continue in-
  • Phase IV, which provides further data on safety and effectiveness in the real world population. This helps physicians and other providers understand the full benefits, risks and optimal use of the drug or device.