Clinical research that is related to developing products for patient care is divided into two preclinical and four clinical phases, each addressing different questions. The knowledge gained at each phase is assessed before progressing to the next. The table below provides an overview of the process. Click each phase to learn more.

Clinical Research does not end when a drug is approved for marketing. Research in the post-marketing phase may continue for several reasons. A regulatory authority may request more studies as a condition for final approval. The sponsor may wish to compare the drug with other active agents for marketing reasons, including cost-benefit ratio for insurance and managed health care purposes. The sponsor may wish to investigate new indications or formulations. The sponsor or the regulatory authority may be interested in surveying safety data in large populations. Phase IV studies involve varying numbers of subjects — anywhere from 50 to several hundred thousand people.

Results of Phase IV studies are often published. Therefore, the data are seen not only by the regulatory authorities, but also by other interested readers, including personnel from competing sponsors, HMOs and physician specialty groups.

Phase IV studies ask the questions:

• Is the drug safe and effective across patients and over time?
• Is the drug as or more effective than other drugs of its kind?
• In examining the larger population, what serious adverse events (AEs) occur? (e.g., BEXTRA, VIOXX).

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