What are Clinical Trials (Studies)?

A clinical trial is a research study involving human volunteers, in an effort to answer specific health questions. Clinical trials are the safest and fastest way to find effective treatments and new ways to improve health.

Clinical trials are conducted according to a plan called a protocol. A protocol describes what types of patients may enter the study, schedules of tests and procedures, drugs and devices, dosages, length of study, as well as outcomes to be measured. Each person participating in the study must agree to follow the protocol.

Why We Conduct Clinical Trials

Many of the standard treatments and therapies today are based on previous clinical studies. Clinical studies are performed to establish evidence based medicine.

Protocols Test

  • To see if a new drug or device is safe and effective
  • To determine which existing treatments are best
  • To study different ways to use standard (approved) treatments, so they will be more effective, easier to use, and/or decrease side effects
  • To learn how to use the treatment in a different population, such as children, in whom the treatment was not previously tested

Phases of a Clinical Trial

Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. This allows researchers to ask and answer questions in a way that results in reliable information about the drug and protects the patients.

Clinical trials are usually classified into one of three phases:

  • Phase I Trials: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the muscle), how often, and what dose is safe. A phase I trial usually enrolls only a small number of patients, sometimes as few as a dozen.
  • Phase II Trials: A phase II trial continues to test the safety of the drug, and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular disease.
  • Phase III Trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard. A participant will usually be assigned to the standard group or the new group at random (called randomization). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, and clinics nationwide.
  • Phase IV trials: Phase IV trials are also known as Post Marketing Surveillance Trials. They involve the safety surveillance and ongoing technical support of a drug after it receives permission to be sold. The safety surveillance is designed to detect any rare or long-term adverse effects over a much larger patient population and longer time period than was possible during the Phase I-III clinical trials.


Each study follows specific guidelines for who can participate. Generally, participants are alike in key ways – such as the type of disease, age, gender and other factors.


Information about you and your participation in a research study will be kept as confidential as possible. Information will be given only to those who have permission to see your records. This may include the group sponsoring the study and those who make sure the study is safe and carried our according to the research plan. Some studies are reviewed by the Food and Drug Administration (FDA). You will sign a study consent allowing the researchers access to your data.

Researchers review and analyze data collected during the study. Results of the studies are sometimes published in medical journals, but your identity will not be revealed.