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Clinical Trial Glossary

Adverse Drug Reaction (ADR)

Any unintended reaction to a new treatment or drug when taken at doses typically used for diagnosis, therapy of disease, prophylaxis or for modification of physiological function, which may occur suddenly or develop over time.

Adverse Event (AE)

When a participant or patient has an undesirable or negative experience associated with a drug or treatment during a clinical trial. Adverse events can include the worsening of a pre-existing condition or the presence of symptoms that were previously unnoticed.

Bioavailability Study

A study which measures the rate and degree to which a drug is absorbed or available to the treatment site in the body.

Bioequivalence Study

A study which tests the same drug manufactured by two different companies to show that the two drugs are bioequivalent (the two drugs do not significantly differ in similar studies under similar conditions with the same dosage).


Any substance (serum, toxin, vaccine, etc.) used to treat, prevent or cure diseases in man.


The use of living organisms and their substances and other biological systems to create or change a drug or other product, to change plants or animals or to develop microorganisms.


A procedure in which one or more parties in a clinical trial are unaware of the treatment assignments in order to decrease biases and avoid the placebo effect. See also, Single Blind and Double Blind.

Case Report Form (CRF)

A document used to record all pertinent information required by the clinical study protocol on each subject in a trial to be reported to the sponsor.

Certified Research Coordinator (CCRC)

A research coordinator with two or more years of experience and who has passed the required program and exam to earn their certification.

Clinical Investigation

See Clinical Trial

Clinical Pharmacology

The science of drugs and their clinical use in man.

Clinical Research

The study of drugs or treatments in human subjects that can be separated into therapeutic (where personal benefit is expected by the subject) and nontherapeutic (where the research is conducted to advance knowledge without the expectation of providing any benefit to the subject).

Clinical Research Associate (CRA)

A person who is employed by a sponsor or contract research organization to monitor the progress of the clinical study at all participating sites. See also, Monitor

Clinical Research Coordinator (CRC)

A person who manages the majority of the administrative duties of a clinical trial. These duties, such as reviewing all data and records, are assigned by the investigator.

Clinical Study Materials

A complete set of study supplies such as study test article, laboratory supplies, case report forms, etc. given to an investigator by the sponsor.

Clinical Trial/Study

A systematic study used to evaluate a drug, treatment or device in one or more human subjects in the treatment, prevention or diagnosis of a disease or condition. This investigation is used to determine or confirm the clinical, pharmacological, pharmacokinetic and/or other pharmacodynamic effects of the investigational products, as well as identify any adverse reactions to determine their safety and efficacy.


Group of subjects in a clinical trial with some characteristics in common who are followed up at standard, preset intervals.

Consent Forms

A document that outlines all the potential risks, benefits and relevant information about a clinical study to the volunteer or participant. This document also details the involved parties’ rights and responsibilities. This document is signed by the volunteer/participant.

Control Group

The group of individuals in a clinical study who do not receive the new treatment or drug, but instead are administered no treatment, an existing treatment or placebo. The control group is the standard by which experimental observations are measured and evaluated.

Controlled Study

A study in which a new drug or treatment is tested against a treatment with known effects. One group receives the new treatment, while the other group receives no treatment, a standard treatment or a placebo.

Crossover Study

A study in which each participant receives both treatments, the new treatment and the control, in a randomized order so that treatment comparisons can be made within each participant.

Data Management

The process by which data is handled and monitored during clinical studies.

Declaration of Helsinki

The international standard of guidelines for the protection of clinical trial participants’ rights, adopted by the 18th World Medial Assembly in 1964. These basic principles are designed to guide physicians conducting biomedical research involving human subjects.

Demographic Data

Characteristics of subjects including sex, age, family medical history and other characteristics pertinent to the study in which they are participating.


An instrument, apparatus, machine, implement or similar article designed for use in the diagnosis, treatment, prevention or cure of a disease or condition.


All records, in any form, that describe or document methods, conduct and results of a study.

Dosage Regimen

The schedule of doses, including the number of doses given in a time period; the elapsed time between each administered dose, or the time at which the doses are given; and the amount of medicine administered at each dosing time.


A clinical study in which neither the investigators nor the participants are aware of which treatment (the new treatment vs. the control) a subject is receiving as to produce objective results and reduce any potential biases from any involved parties.


A substance (other than food) used in the diagnosis, treatment, cure or prevention of disease; used to enhance mental or physical well-being; or used to affect the function or structure of the body in humans or animals.

Drug Product

The finished dosage form (i.e. capsule, tablet, solution, etc.) that contains a drug substance in combination with other active or inactive ingredients.

Effective Dose

The dose of an investigational drug or treatment that produces the desired outcome considered effectual as outlined by the study protocol.


A drug or treatment’s maximum ability to produce beneficial results regardless of dosage on the course or duration of a disease or condition.

Ethics Committee

See Institutional Review Board

Exclusion Criteria

A list of characteristics or criteria, any one of which that would exclude a participant from a clinical study as outlined in the study protocol.

Experimental Drug

A drug that is not licensed by the FDA for use in humans or as a treatment for any disease or condition.

Food and Drug Administration (FDA)

The United States regulatory authority within the Department of Health and Human Services responsible for enforcing the safety and efficacy of all drugs, medical devices, biologics and vaccines and granting IND and NDA approvals.

Food Drug and Cosmetic Act (FD & C Act)

This act states that only drugs, devices and biologics with proven efficacy and safety can be marketed.


The combination of biological substances and/or chemicals used to make dosage forms such as tablets, capsules and solutions.

Generic Drug

A drug with the same molecular structure and active ingredient, but not necessarily the same inactive ingredients, as a brand-name drug. A generic drug can only be marketed after the original drug’s patent has expired and typically costs less than the proprietary brand.

Good Clinical Practice (GCP)

An international standard of guidelines and regulations used to ensure protection of subjects’ rights, confidentiality and integrity and the accuracy and credibility of data in clinical studies.

Half-Life of a Drug

The amount of time taken for the concentration of a drug in the body to decline by half.

Healthy Volunteer

An individual in good health who participates in a clinical study who does not receive health benefits from participating and is participating for reasons other than medical.

Human Pharmacology

The study of uses, actions and undesirable side effects of drugs in humans, which typically follows pharmacological studies on animals.

Human Subject

A healthy individual or patient who becomes a participant in a research study.

ICH-International Conference of Harmonization

ICH is focused on the harmonization of technical requirements for the registration of pharmaceutical products in the U.S., Japan and European Union.

Inclusion Criteria

The criteria which all subjects must meet in order to be eligible to participate in a clinical study.

Informed Consent

The patient’s confirmation of his or her willingness to participate in a clinical trial, along with written, signed and dated documentation. This verification is requested only after all key aspects of the clinical trial have been explained objectively by doctors and nurses.


The location of clinical research.

Institutional Review Board (IRB)

An independent group of both medical and non-medical professionals who ensures a clinical study’s safety and efficacy for human participation. The IRB ensures that the clinical trial is ethical, that the rights of subjects are protected and that the study complies with the FDA’s regulations.

Investigational New Drug Application (IND)

The request through which a sponsor appeals to the FDA to allow human testing of its new drug product.

Investigational Product

An active ingredient or placebo in pharmaceutical form being tested in a clinical trial, which includes a marketed product used in a dissimilar manner than the approved form, when used for an unapproved indication or when used to acquire more information about an approved use.


A trained scientist or medical professional under whose immediate direction an investigational drug is administered, dispensed or used at a trial site.

Investigator’s Brochure

A collection of the relevant clinical and non-clinical data on the investigational product(s) involved in a clinical study.

Marketing Studies

Studies (most commonly Phase IV studies and some Phase III studies) which are executed to deliver clinical trial data to promote the product in the marketplace after the drug has been granted a license.

MedWatch Program

FDA program designed to monitor adverse events (AE) from drugs marketed in the U.S. through the online database known as the Adverse Event Reporting System (AERS). With MedWatch, health professionals and consumers can send adverse event reports voluntarily to the FDA. Drug manufacturers are obliged by regulations to report all AEs brought to their attention. The fundamental goal of AERS is to provide the tools for storing and analyzing safety reports to improve public health.


Person employed by the sponsor or CRO who verifies that a clinical study is being conducted in accordance with the protocol by assisting with the planning and initiation of a study and reviewing reports to assess the conduct of studies, among other duties. See also, CRA.


The act of supervising a clinical study, ensuring all aspects of the trial are conducted as stated in the clinical protocol, standard operating procedures, good clinical practice and by regulatory requirements.

Multicenter Study

A single protocol clinical study conducted at more than one site and by more than one investigator.

Multicenter Trial

See Multicenter Study

National Research Act

An act that created the National Commission for Protection of Human Subjects of Biomedical and Behavioral Research in 1974 to supervise and control the use of human experimentation in medicine and required the review of studies and participant’s protection by informed consent.

National Institutes of Health (NIH)

Primary agency within the United States Department of Health and Human Services that is responsible for biomedical and health related research. The NIH also provides funding for and conducts studies.

New Drug Application (NDA)

A request from the manufacturer of a drug to the FDA for a license to market a new drug in the U.S. Within this application, a comprehensive collection of all information about the new drug that was compiled in the clinical trial must be presented.

Nuremberg Code

A code of medical ethics set forth in 1947 for conducting human medical research in clinical trials. The code is designed to protect the safety of participants in a clinical study.

Off Label

The unapproved use or prescription of a drug for a purpose or condition other than that approved of by the FDA.

Open-Label Study

A study in which no blind is used, and all parties are aware of the drug and dose being administered and received. Open-label studies are the opposite of double blind studies.

Orphan Drug

An FDA category which refers to drugs and treatments for rare diseases and conditions, or those which affect less than 200,000 people in the U.S. Orphan drugs have little financial incentive because they will help such a small population of people, so the U.S. government offers other incentives to drug companies for the development of these drugs.

Over-the-Counter (OTC)

Medicine that is available without a visit to a medical professional and/or without a prescription.

Parallel Group Study (Trial)

A study in which two or more treatments are compared by randomly assigning participants to one of two treatment groups, which will receive the allocated medication throughout the duration of the study.


An individual seeking medical care or who is under physician care for a condition or disease.


The study that compares the value of drugs with other therapies or with similar drugs in terms of their financial and quality of life cost and effects. Also known as “outcomes research.”


The study of the effects of drugs on the body and/or living structures and the relationship between drug absorption and effect.

Pharmacokinetic Study

The study of the processes of bodily absorption, distribution, metabolism and elimination of a drug or medicine.


The study of how drugs interact with living organisms, such as the characteristics, effects and uses of the medications.

Phase I Study

Phase I studies are conducted on healthy volunteers to establish the effects of a new drug in humans. These initial studies are conducted to determine the safety and tolerability of a drug, as well as the drug’s toxicity, absorption, distribution and metabolism.

Phase I Unit

The facility which has been specifically designed and custom-built for conducting studies with normal, healthy participants/volunteers.

Phase II Study

Phase II studies are controlled studies conducted to test the safety and efficacy of a drug on a larger population of patients who are afflicted with the condition or disease the drug is targeting.

Phase III Study

Phase III studies are large, multicenter studies of afflicted patients which test the new drug in comparison with a placebo or the standard therapy most commonly used to treat the condition or disease. Phase III studies gather additional information to further evaluate the efficacy and safety of a new drug.

Phase IV Study

Phase IV studies are post-marketing studies conducted to gain additional information about a drug’s safety and efficacy and to compare the drug to competitors in the market – after the drug has been approved by the FDA.

Pilot Study

A small study conducted to determine the practicality of taking on a larger clinical trial.

Pivotal Study

A controlled, randomized study conducted to good clinical practices and subjected to intense monitoring to ensure its validity in order to provide critical information to authorities about the efficacy and safety of a new drug.


A pharmaceutical substance that contains no active ingredient and is designed to look just like the drug being tested. Placebos are used as controls in clinical studies.

Pre-Clinical Testing

Animal studies conducted to acquire information about safety and tolerance of drugs before conducting human testing in clinical trials.


A document that sets forth the objective(s), design, organization, statistical considerations and methodology for a clinical trial. A protocol must be approved by an IRB before the study can be conducted.

Protocol Amendment

Written augments or clarifications of a protocol, which also must be approved by the IRB.

Quality Assurance

The procedures and control systems established to ensure a study adheres to good clinical practice (GCP) guidelines and to ensure the protection of the trial participants.

Random Allocation

The assignment of subjects to treatment or control groups in an unsystematic manner.


The process by which trial participants are assigned to treatment or control groups in an unsystematic manner and by method of chance to reduce the likelihood of bias.


The process of identifying and enrolling suitable participants in a clinical trial.

Recruitment Period

The time period in which investigators must complete enrollment of participants for a clinical study.

Regulatory Affairs

A department that is responsible for ensuring adherence to government regulations in clinical trials.

Research Team

Within a clinical study, the research team is the investigator, subinvestigator and clinical research coordinator involved.

Run-in Period of Study

The period of time used to take patients off their existing medications in order to prepare them to be treated with a new drug. This may be accomplished through the administration of a placebo for up to two weeks.

Safety Reports

In the event of any serious and/or unexpected adverse experience, the FDA requires a report.

Serious Adverse Event (SAE)

Any adverse event (AE) that is life threatening, permanently disabling or which results in hospitalization or leads to death.

Side Effect

Any actions or effects of a drug or treatment that are different from the intended effects. Side effects can be negative, neutral or beneficial to the subject.

Single Blind Study

A study in which one of the parties (investigator or participant) is unaware of what medication subjects are receiving.

Source Data

All information contained in original records and certified copies (source documentation) of findings, observations or other activities in a clinical trial mandated for the reconstruction and evaluation of the study.


Organization or individual that takes responsibility for initiation, management and/or financing of a clinical trial.

Standard Operating Procedure (SOP)

Detailed, written descriptions for the management of clinical trials that must be adhered to during a study. SOPs ensure the uniformity of all the functions and activities of a clinical trial.

Standard Treatment

The treatment currently accepted and widely used (FDA approved) as the effective treatment of a condition or disease.

Study End Point

A primary or secondary result used to evaluate the efficacy of a treatment.


An individual member of the clinical study team who performs essential trial procedures and/or makes important trial-related decisions.

Subject/Study Subject

See Human Subject.

Washout Period

The period of time in a clinical trial when patients are given a placebo or no drug at all to eliminate the effects of the first treatment before starting the second active treatment.

Common Questions:

What is a Clinical Research Trial?
Why Participate in a Clinical Research Trial?
Is there a difference between Clinical Trials and Treatment?
How are New Drugs Tested?

Learn More About Clinical Trials:

What Types of Clinical Trials are Available?
Phase I Clinical Trials
Phase II Clinical Trials
Phase III Clinical Trials
Phase IV Clinical Trials
Alabama Health Resources
Brief History of Clinical Trials
Find Clinical Trials

Know Your Rights as a Participant:

Your Patient Rights
Patient Privacy Rules
Informed Consent Agreement
NIH Patient Bill of Rights
Legal, Ethical, and Safety Issues