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Clinical Trials

A clinical trial is a research study used to evaluate the safety and efficacy of medical interventions. These interventions are often new drugs, medical devices or procedures; however, they can also include programs, health delivery systems, and behaviors. Participants involved in clinical trials are usually assigned to receive either a medical intervention or control option. The controls often receive an alternative therapy or placebo but may receive no intervention when an acceptable alternative is not available. Investigators then try to determine whether the outcomes in the intervention group are better, worse, or the same as those in the control group.

Prior to being approved for use in the U.S. by the Food and Drug Administration (FDA), most new medical treatments must undergo at least three clinical trial phases. These phases are defined as follows:

  • Phase I: New drug or treatment is evaluated for safety, dosage, and side effects in a small group of volunteers
  • Phase II: New drug or treatment is evaluated for effectiveness and safety in a larger group of volunteers
  • Phase III: New drug or treatment is evaluated to confirm effectiveness and safety, monitor side effects, and compare with existing treatments in even larger groups of people in the general population
  • Phase IV: New drug or treatment is evaluated post-marketing to monitor side effects and collect additional information on the performance of the drug in the general population

For more information on clinical trials as well as a listing of both public and private clinical trials being conducted worldwide, please visit