Understanding Clinical Trials PDF Print E-mail

Testing the Safety and Efficacy of New Medicines

Clinical trials, or studies, serve as a foundation to determining whether a new drug is safe and effective. The U.S. government, as well as other worldwide jurisdictions, require data from these trials before a drug is approved and then sold. In these studies, medical professionals evaluate the drug in order to determine whether it is safe and if it could improve the health of patients.

The clinical development of a drug is organized into specific steps or phases. Each of these phases is designed to answer different questions, and as those questions are answered satisfactorily, a drug may advance to the next phase until it is shown in all of the studies to be safe and effective.

Phase I

Phase I studies are safety studies. This represents the first time that the drug is being evaluated in human volunteers. These studies generally involve a small number of volunteers to assess how much of the drug could be used in future studies.

Phase II

Phase II studies measure the effectiveness of the drug to treat the intended disease. This phase enrolls a larger number of patients than Phase I and will also continue to monitor the safety of the drug.

Phase III

A Phase III study is the most advanced phase with the largest enrollment and compares the safety and effectiveness of the drug against the current standard treatment in treating the disease.

Phase IV

Phase IV or “post-marketing” studies are conducted after the approval of a drug and are focused on following the drug and patients for a predetermined duration in order to ensure the safety of patients using the marketed drug.

Regulation and Oversight

Clinical studies are regulated by the government and also the study doctors who work in them. Before a study can begin to enroll patients, it must be reviewed by an independent group of scientists and community members called an Institutional Review Board or IRB. The IRB reviews the study to make sure that it is as safe as possible for the study volunteers. They also review the plan for guarding patients' confidentiality and privacy.

Enrolling In or Learning About Clinical Studies

If you're looking for a clinical study, either to enroll, or for more information or results, there are a number of options, such as: