How Clinical Trials are Conducted

Clinical trial phases and potential risks

Clinical Trials are Conducted in Phases

Each clinical trial is conducted in four phases. The Food and Drug Administration (FDA) must approve each phase before the study can continue.

  • Phase I: In this phase, a new drug or treatment is tested on a small group of healthy people to determine safe dosage, study how the drug works in the body, and see if it has any side effects. The overall safety of the drug is not known during this phase.
  • Phase II: The drug or treatment can now be tested on a larger group of people to see if it is effective and to further test its overall safety. Rating scales are developed and used to record data during this phase.

clinical practice guidelines are applied to medical studiesClinical practice guidelines are essential throughout all phases of a clinical trial's study of a drug or medical device. Photo Source:

  • Phase III: Now the drug or treatment is ready to be tested on even larger numbers of people. The study will look even more closely at the drug's effectiveness, if it has any side effects, overall safety, and how it can improve a person's quality of life. Most drugs that reach this phase are considered for FDA approval.
  • Phase IV: Once given FDA approval, the trial can enter into the final phase, which involves monitoring the drug after it has been released to the public. In this phase, researchers look for additional information such as risks, benefits, and optimal or additional uses of the drug. In some cases this phase is used to test the drug on a sub-group of people (such as patients over a certain age).

How Clinical Trials are Conducted

Depending on the type of study you participate in, the clinical trial is conducted by a team that includes doctors, nurses, social workers, researchers, and other health care professionals. Once you have been given approval to participate, the trial will follow this general procedure:

  • You will be seen by the researchers before the trial to get your health history and assess your overall health.
  • You will be given specific instructions about how to participate (this is called the study protocol).
  • During the length of the trial you will be monitored. This may involve numerous doctor visits, tests, or other procedures.
  • Once the trial is completed, you will be able to stay in touch with the team for follow-up treatment information.

Potential Risks of Participating in a Clinical Trials

Clinical trials are an important (and sometimes the only) way to test a new medication or treatment. However, participants must be aware of the risks and safety measures steps during a clinical trial.

  • Participants may experience unpleasant, serious, or even life-threatening side effects of the drug or treatment being studied.
  • The treatment may not work.
  • The requirements of the study may be more than the participant thought. Every clinical trial has a protocol, which is the plan on which the entire study is based. The protocol describes exactly what the participants must do during the trial such as how often they need to see the research staff, how much of the drug they need to take, what other procedures they must follow, and how long the trial will last. Sometimes, particularly for participants who are not in good health, these activities take up a good deal of time and attention.

Safety Measures Help Minimize Risks

  • All clinical trials that involve human participants in the United States are approved and monitored by an Institutional Review Board (IRB). This is a group of doctors, researchers, community advocates, and others who ensure the ethical nature of the trial and make sure that the rights of the study participants are protected.
  • The IRB reviews all study-related documents such as the protocol, participant recruitment announcements, and consent forms.
Updated on: 07/03/19
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