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What Are Clinical Trials & Other Questions

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What Are Clinical Trials?

Clinical trials or research studies are organized tests of medicines and new treatment options. These studies rely on patient volunteers who try the new or changed treatment. Sometimes they are new experimental medicines that have not been approved by the FDA for sale in the United States. Sometimes they are drugs that are currently available for sale but are being tested for a new disease or new doses of the same medicine.

Not all doctors choose to do clinical trials. You may enter a trial with your own doctor or with another local doctor who is running a trial you are interested in. If you go to a doctor other than your own, you are always free to go back to your own doctor for your routine medical care.

Questions relevant to the trial should always be addressed to the trial doctor for the duration of your trial participation. Any clinical trial participation is always voluntary. In most clinical trials the treatment, office visits, and all tests are free. You may also be given financial compensation for participating in some cases. Your doctor or the study coordinator at your doctor's office should share information regarding the compensation package with you during your first visit.

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 experimental treatments with the most promising laboratory results are moved into clinical trials. During a trial, more and more information is gained about an experimental treatment, its risks and how well it may or may not work.

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.

What Is Clinical Research

Types, Phases, & Protocols of Clinical Trials

Clinical Trial Types

Treatment trials test experimental 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 lifestyle changes.

Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular disease or condition.

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.

How do drugs and procedures qualify for clinical trials?

Patients who participate in a clinical trial receive drugs or procedures that already have been research in successful laboratory and/or animal studies. Most clinical trials study new drugs or procedures, but some study drugs or procedures that have already received approval by the US Food and Drug Administration.

Phases in Clinical Trials

Most clinical trials are carried out in steps called phases. Each phase is designed to find different information. Patients may be eligible for studies in different phases depending on their general condition, the type and stage of their condition, and what therapy, if any, they have already had.

Patients are seen regularly to determine the effect of the treatment, and treatment is always stopped if side effects become too severe. (Please continue for a description of each of the four phases involved in a clinical trial.)

Phase I Trials

Phase I studies are primarily concerned with assessing the drug's safety. This initial phase of testing in humans is done in a small number of healthy volunteers (20 to 100), who are usually paid for participating in the study. The study is designed to determine what happens to the drug in the human body—how it is absorbed, metabolized, and excreted.

A phase I study will investigate side effects that occur as dosage levels are increased. This initial phase of testing typically takes several months. About 70 percent of experimental drugs pass this initial phase of testing.

Phase II Trials

Once a drug has been shown to be safe, it must be tested for effectiveness. This second phase of testing may last from several months to two years and involve up to several hundred patients.

Most phase II studies are randomized trials. One group of patients will receive the experimental drug while a second control group will receive a standard treatment or placebo. Often these studies are blinded—neither the patients nor the researchers know who is getting the experimental drug.

In this manner, the study can provide the pharmaceutical company and the FDA comparative information about the relative safety of the new drug and its effectiveness. Only about one-third of experimental drugs successfully complete both phase I and phase II studies. Safety continues to be evaluated.

Phase III Trials

In a phase III study, a drug is tested in several hundred to several thousand patients. This large-scale testing provides the pharmaceutical company and the FDA with a more thorough understanding of the drug's safety, effectiveness, benefits, and the range of possible adverse reactions. Most phase III studies are randomized and blinded trials.

Phase III studies typically last several years. Seventy to 90 percent of drugs that enter phase III studies successfully complete this phase of testing. Once a phase III study is successfully completed, a pharmaceutical company can request FDA approval for marketing the drug.

Phase IV Trials

In late phase III/phase IV studies, pharmaceutical companies have several objectives:

  1. studies often compare a drug with other drugs already in the market;
  2. studies are often designed to monitor a drug's long-term safety, effectiveness and impact on a patient's quality of life; and
  3. many studies are designed to determine the cost-effectiveness of a drug therapy relative to other traditional and new therapies.


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.

Clinical Trials Terminology

Institutional Review Board (IRB): A board consisting of health care professionals from the institution where the clinical trial takes place, as well as members of the local community. The board scrutinizes all trial activities including recruitment, advertising, and potential risks. The IRB also makes sure that FDA regulations are being followed in a particular trial.

Clinical Investigator: A medical researcher in charge of carrying out a clinical trial's protocol. Researchers are usually doctors, nurses, pharmacists, or other health care professionals.

Food and Drug Administration: A government agency that enforces laws on the manufacture testing and use of drugs and medical devices. All drugs and medical devices must be approved by the FDA before they can be used by the general public.

Placebo: An inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the experimental treatment's effectiveness. In some studies, the participants in the control group will receive a placebo instead of an active drug or experimental treatment.

Control or Control Group: 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.

Meet Research Participants


Connecting Volunteers & Researchers

University of Utah Health participates in ResearchMatch, a secure place for volunteers and researchers to find one another.