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Clinical Trial Glossary

Clinical Trial Glossary Final - FDA
Glossary of terms on clinical trials

Clinical Trials: What Patients Need to Know > Glossary of Terms - FDA


Adverse Event - drug reaction is also known as a side effect, is any undesirable experience associated with the use of a medicine in a patient. Adverse events can range from mild to severe. Serious adverse events are those that can cause disability, are life- threatening, result in hospitalization or death, or are birth defects.

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Boxed Warning - This type of warning is also commonly referred to as a “black box warning.” It appears on a prescription drug’s label and is designed to call attention to serious or life-threatening risks.

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Cardiovascular disease– also called heart disease is a class of diseases that involve the heart, the blood vessels (arteries, capillaries, and veins) or both.

CDRH– (Center for Devices and Radiological Health) assure that patients and providers have timely and continued access to safe, effective, and high-quality medical devices and safe radiation-emitting products.

ClinicalTrials.Gov- is an online registry of clinical trials that are being conducted around the world. is operated by the National Library of Medicine at the National Institutes of Health and can be accessed by anyone who has access to the internet.

Comparison– To learn more, researchers compare results from patients in the experimental groups with results from patients in the control groups.

Compassionate Use - Expanded access, also called “compassionate use,” provides a pathway for patients to gain access to investigational drugs, biologics and medical devices for serious diseases or conditions. Investigational drugs and devices have not yet been approved by the FDA and they have not been proven to be safe and effective. Therefore, they may be effective in the treatment of a condition, or they may not. It is important to remember that the drug/biologic/medical device may have unexpected serious side effects and that patients need to consider all the possible risks when seeking access to an investigational medical product.

Clinical Trials Glossary of CommonlyUsed Terms


The ability of a drug or treatment to produce a beneficial result. A drug demonstrates efficacy if it is effective at the dose tested against the illness for which it is prescribed.Eligibility criteriaThe key standards that people who want to participate in a clinical study must meet or the characteristics they must have.