Back to: Clinical Center home page < Profile 2005

Advancing clinical research

Protocols by research type (onsite intramural protocols, fiscal year 2004)
Clinical studies are medical research studies (or protocols) in which human volunteers participate. Clinical trials are studies developing or investigating new treatments and medications for diseases and conditions. Natural history studies investigate normal human biology and the development of a particular disease. Screening studies determine if individuals may be suitable candidates for inclusion in a particular study. Training studies provide an opportunity for staff physicians and other healthcare professionals to follow particular types of patients.

Clinical trials proceed through four phases
Phase I:
Researchers test a new drug or treatment for the first time in a small group (20–80) of people to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase II:
The study drug or treatment is given to a larger group (100–300) of people to see if it is effective and to further evaluate its safety.
Phase III:
The study drug or treatment is given to large groups of people (3,000 or more) to confirm its effectiveness, monitor side effects, compare it with commonly used treatments, and collect information that will ensure safe usage.
Phase IV:
These studies are done after the drug or treatment has been marketed. Researchers continue to collect information about the effect of the drug or treatment in various populations and to determine any side effects from long-term use.

Breakdown of clinical trials