A clinical trial is a scientific experiment that is done with people who volunteer to participate. Like any scientific experiment, the conditions of a clinical trial are carefully controlled and closely monitored. For example, study volunteers must fulfill enrollment criteria in order to be eligible for participation. The criteria are determined with consideration to the validity of the research results and the safety of the volunteers. In general, the purpose of clinical trials is to evaluate the safety, effectiveness or best dosage schedule of experimental drugs or medical devices in persons having a specific disease or health condition.
New drugs have to be evaluated before they are given to the general population.
The safest and most effective way to evaluate drugs is in the format of a clinical trial. Often a clinical trial is designed so that neither the study volunteer nor the medical staff knows if the study volunteer is actually receiving the experimental drug. A study is blinded in order to eliminate the possibility of unfairness in the assessment of the effectiveness of the study drug. In a blinded study, the study volunteers are randomized, that is they are randomly assigned to receive the study drug or something that looks like the study drug. This might be a standard drug that has been reformulated to look like the study drug, or it might be a placebo.