An unfavorable change in the health of a participant, including abnormal laboratory findings, that happens during a clinical study or within a certain time period after the study is over.

A clinical trial design strategy in which one or more parties involved with the trial, such as the investigator or participant, do not know which participants have been assigned which study treatment.

Clinical research is medical research that involves people to test new treatments and therapies.

A drug that has not been approved by the FDA and can only be used in a research study that has been approved by an IRB.

An agency within the U.S. Department of Health and Human Services. The FDA is responsible for protecting the public health by making sure that human and veterinary drugs, vaccines and other biological products, medical devices, the Nation's food supply, cosmetics, dietary supplements, and products that give off radiation are safe, effective, and secure.

A healthy volunteer is a person with no known significant health problems who participates in clinical research to test a new drug, device, or intervention.

Inclusion criteria are factors that allow someone to participate in a clinical trial. Those that exclude or do not allow participation are exclusion criteria.

The process used to inform the participant about the risks and potential benefits about a clinical trial before someone decides whether to participate.

The IRB and IEC are independent committees of healthcare professionals, researchers, statisticians, and community advocates. By federal law, all clinical trials must be approved by an IRB in the United States and by the IEC in Belfast, Northern Ireland. The IRB/IEC will review the proposed trial weighing the potential risks and benefits and making sure that the rights and welfare of trial participants are protected.

Describes a clinical trial in which blinding is not used. This means that all parties involved with the trial know which participants have been assigned which study treatment.

Clinical trials are conducted in “phases.” The trials at each phase have a different purpose and help researchers answer different questions.

Phase I trials—An experimental drug or treatment in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.

Phase II trials—The experimental drug or treatment is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.

Phase III trials—The experimental drug or treatment is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments.

Phase IV trials—After a drug is licensed and approved by the FDA researchers track its safety, seeking more information about its risks, benefits, and optimal use.

A placebo is a pill or liquid that looks like the new treatment but does not have any treatment value from active ingredients.

A protocol is a formal design or plan of an experiment or research activity. The protocol includes a description of the research design to be used, the eligibility requirements for prospective participants and controls, the treatment, the plan to safeguard the participants’ health, and the proposed methods of analysis that will be performed on the collected data.

A Principal Investigator is a doctor who leads the clinical research team and, along with the other members of the research team, regularly monitors study participants’ health to determine the study’s safety and effectiveness.

Randomization is the process by which two or more alternative treatments are assigned to volunteers by chance rather than by choice.

Single- or double-blind studies (also called single- or double-masked studies) are studies in which the participants do not know which treatment is being used, so they can describe what happens without bias.

The organization (a pharmaceutical or biotechnology company) that oversees and pays for the clinical study.

Compensation received for participating in a clinical Trial.

The person who is the main contact for the study and for ensuring that the study is conducted correctly.