FAQ: Phases of Clinical Trials
What are the different phases of clinical trials?
Clinical Trials are conducted in different phases. The trials at each phase have a different purpose and help scientists answer different questions:
Phase I
trials are performed to test an experimental drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage, and to evaluate side effects;
Phase II
trials are carried out where the experimental 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;
Phase III
trials are conducted where the experimental 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 permit the experimental drug or treatment to be used safely;
Phase IV
trials are conducted for post-marketing studies to delineate additional information including the drug's risks, benefits, and optimal use.
How long it will take to complete a clinical trial?
Clinical trials can be completed in months or it can take years. It always depends on the disease/condition being treated or how long it will take to measure the efficacy, safety or side effects of a drug being tested.
During the study, the
subjects
will be closely monitored and will be required to return to the research center for one and up to several visits, depending on the study protocol.
What is a protocol?
A protocol is a study plan to conduct clinical trials or investigations. The plan is carefully designed to safeguard the health of the
subjects
as well as answer specific research questions. A protocol describes who may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study.
What is a control group?
In many clinical trials, one group of
subjects
will be given an experimental drug or treatment, while the control group is given either a standard treatment for the disease/condition or a placebo.
What is a placebo?
A placebo is an inactive pill, liquid, or powder that has no treatment value (inactive substance). In clinical trials, experimental treatments are often compared with placebos to assess the experimental treatment's effectiveness. In some studies, the
subjects
in the control group will receive a placebo instead of an active drug or experimental treatment.
The reason why
subjects
are given a placebo is because scientists should be able to tell if there is a difference between those who get the study drug or experimental treatment and those who do not. Neither the
subjects
nor the doctors and scientists know who gets the study drug or treatment and who gets the placebo until after the trial is completed, which makes the trial ‘double-blinded’.
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