A clinical trial is a specific kind of research study that involves careful examination of the effects of a drug (or other treatment) administered to humans. Usually, some participants are given the test drug while others are given an alternative drug or a placebo; no participant knows which kind of treatment he or she is receiving. The researcher then determines whether the benefits of the test drug are significantly greater than the alternative drug or placebo.

For example, if a company has developed a new compound which it feels will prevent migraines better than an existing drug, or do just as well with fewer side effects, it may organize a clinical trial of the new compound. A group of migraine sufferers are recruited to participate, and they may be paid for their time. Each participant is asked to take a series of pills over a period of time -- without knowing whether they have been given is the test compound or the existing drug. During the study, each participant reports when and if they experience migraine. If the participants using the test compound report infrequent and mild headaches while the participants using the existing drug complain about frequent, severe migraines, then the researchers would conclude that the test compound is effective and should be made available for general medical use to treat and prevent migraines.

The goal of clinical trials is to determine both the efficacy of the drug and also whether it has side effects, toxicity and/or adverse interactions with other drugs. The U.S. government has very strict standards for these studies, and for how the results are to be evaluated, before a drug is approved for use in the United States. Every year, many compounds that are developed by pharmaceutical companies fail clinical trials, meaning that they do not pass the high standards for efficacy and safety, and never reach the market.

Further Reading:

Article : "THE BRAIN TREE"

Article : "ESTROGEN AND ALZHEIMER'S"

Article : "PUTTING GINGKO TO THE TEST"