A clinical trial is a carefully designed study that is performed with volunteers who receive investigational drugs. These studies are done under the careful supervision of the U.S. Food and Drug Administration (the FDA), biotechnology companies, clinical investigators (physicians who are specialists in their field and selected because of skill and interest in clinical investigation) and local Institutional Review Boards (IRB’s) composed of professional and lay people.   These various levels of supervision intend to provide for the safety of the volunteers and insure that the scientific data collected is meaningful in the evaluation and testing of the investigational compounds.   Clinical trials come in four different phases:   Phase 1 studies determine whether the investigational drug is safe and can be tolerated by human subjects. In these studies a small number of healthy subjects are given the investigational drug and various doses are tried to see what humans can tolerate. FHRC does not do Phase 1 trials.   Phase 2 studies test the safety and effectiveness of the drug on human volunteers who have the condition the drug is supposed to treat. For example, if the drug is an antidepressant, the volunteers must be determined to suffer from depression according to very strict diagnostic guidelines. In this phase, the studies are usually double blind studies.   Double blind studies require that the subject and the investigator do not know whether the subject is receiving the investigational drug or a placebo (an inactive substance, a so-called "sugar pill"). This double blinding insures complete scientific objectivity. Neither the expectations of the subject nor those of the investigator will bias the outcome of the study. When the term of the study is completed (often several years later) the blind is broken and the subject and the investigator both find out which substance the volunteer was taking. When the volunteer completes the study, Dr. Feiger may, if necessary, continue treatment for up to four months using drugs currently approved by the FDA.   FHRC participates in many Phase 2 trials.   Phase 3 trials determine the effectiveness of the drug on large numbers of subjects and also look for side effects associated with the drug which were not detected in the earlier trials. Phase 3 trials may be double blind or may be "open label".   Open label studies provide the investigational drug to the subject and both the subject and the investigator know that the subject is receiving the drug and at what dose. These studies span longer periods of time, occasionally lasting as long as two years.   FHRC participates in many phase 3 trials.   Phase 4 trials occur once a drug has been approved by the FDA and it is available to the public. These trials continue to document side effects and may look for other indications for the drugs.   On some occasions, FHRC does participate in Phase 4 trials.   The following link has detailed and excellent general information about clinical trials.   www.dbsalliance.org/info/clinical.html