The following frequently asked questions are important in understanding the unique process of clinical trials.
An Introduction to Clinical Trials
Q: What are clinical trials?
A clinical trial is a research study to answer specific
questions about vaccines, new therapies or new ways of using
known treatments. Clinical trials (also called medical research
and research studies) are used to determine whether new drugs
or treatments are both safe and effective. Carefully conducted
clinical trials are the fastest and safest way to find treatments
that work in people.
Q: Why participate in a clinical trial?
Participants in clinical trials can play a more active role in
their own health care, gain access to new research treatments
before they are widely available, and help others by contributing
to medical research.
Q: Where do the ideas for trials come from?
Ideas for clinical trials usually come from researchers. After
researchers test new therapies or procedures in the laboratory
and in animal studies, the treatments with the most promising
laboratory results are moved into clinical trials. During a
trial, more and more information is gained about a new treatment,
its risks and how well it may or may not work.
Q: Who sponsors clinical trials?
Clinical trials are sponsored or funded by a variety of
organizations or individuals such as physicians, medical
institutions, foundations, voluntary groups, and pharmaceutical
companies, in addition to federal agencies such as the National
Institutes of Health (NIH), the Department of Defense (DOD),
and the Department of Veteran's Affairs (VA). Trials can take
place in a variety of locations, such as hospitals, universities,
doctors' offices, or community clinics.
Q: What is a protocol?
A protocol is a study plan on which all clinical trials are based.
The plan is carefully designed to safeguard the health of the
participants as well as answer specific research questions. A
protocol describes what types of people may participate in the
trial; the schedule of tests, procedures, medications, and
dosages; and the length of the study. While in a clinical trial,
participants following a protocol are seen regularly by the
research staff to monitor their health and to determine the
safety and effectiveness of their treatment.
Q: What is a placebo?
A placebo is an inactive pill, liquid, or powder that has no
treatment value. In clinical trials, experimental treatments
are often compared with placebos to assess the treatment's
effectiveness. In some studies, the participants in the control
group will receive a placebo instead of an active drug or
Q: What is a control or control group?
A control is the standard by which experimental observations
are evaluated. In many clinical trials, one group of patients
will be given an experimental drug or treatment, while the
control group is given either a standard treatment for the
illness or a placebo.
Q: What are the different types of clinical trials?
Treatment trials test new treatments, new combinations of drugs,
or new approaches to surgery or radiation therapy.
Prevention trials look for better ways to prevent
disease in people who have never had the disease or to
prevent a disease from returning. These approaches may
include medicines, vitamins, vaccines, minerals, or
Screening trials test the best way to detect certain
diseases or health conditions.
Quality of Life trials (or Supportive Care trials) explore
ways to improve comfort and the quality of life for individuals
with a chronic illness.
Q: What are the phases of clinical trials?
Clinical trials are conducted in phases. The trials at each
phase have a different purpose and help scientists answer
In Phase I trials, researchers test a new drug or
treatment in a small group of people (20-80) for the
first time to evaluate its safety, determine a safe
dosage range, and identify side effects.
In Phase II trials, the study drug or treatment
is given to a larger group of people (100-300) to see if
it is effective and to further evaluate its safety.
In Phase III trials, the study drug or treatment is
given to large groups of people (1,000-3,000) to confirm
its effectiveness, monitor side effects, compare it to
commonly used treatments, and collect information that will
allow the drug or treatment to be used safely.
In Phase IV trials, post marketing studies delineate
additional information including the drug's risks, benefits,
and optimal use.
Used with permission of the National Library of Medicine.