The Four Phases of a Clinical Research Study
The testing of an experimental drug involves four phases:
- Phase I clinical research studies are the first stage of testing in human volunteers. A small group of these otherwise healthy volunteers are screened. This phase assesses the safety and tolerability of a drug.
- A Phase II clinical research study occurs after Phase I studies have been completed successfully. The investigational drug is tested for safety and effectiveness in a larger population of people who have the disease or condition.
- A Phase III clinical research study is the last round of pre-approval testing for an investigational drug. The drug is tested in comparison to a standard or an approved treatment and/or placebo for the disease or condition for which the drug is being researched. The results of these studies usually provide the information for the drug's package insert and label.
- A Phase IV clinical research study occurs after a drug has been approved by the FDA. The drug may be compared with similar medications; it may be evaluated for additional patient populations; or it may be studied for any specific, unusual, or unexpected side effects.
The GAP Study is a Phase III study. It is designed to evaluate the effectiveness, safety, and tolerability of an investigational drug for Alzheimer's. About 360 patients with mild-to-moderate Alzheimer's will participate in this research study.