Clinical trials are conducted in a series of steps, commonly referred to as phases. Each phase is designed to answer a separate research question, a question that must be answered adequately before moving on to the subsequent step.
Phase I Trials are essential to determine if a new drug or treatment is safe at the most basic level. In Phase I Trials, researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects. If a new drug or treatment passes Phase I and is determined to be safe and show some promise, it moves on to a Phase II Trial.
In a Phase II Trial, the drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety. If the new drug or treatment is still considered to be safe and has shown evidence that it is effective in treating disease, it will be moved forward to a Phase III trial.
In a Phase III Trial, the drug or treatment is given to an even larger group of individuals to confirm its effectiveness, monitor side effects, and compare it to other commonly used drugs or treatments. If a new drug or treatment successfully passes its Phase III Trial, it can be moved to market and sold to the public. However, studies of the new drug or treatment may be ongoing.
Phase IV Studies are done after the drug or treatment has been marketed to gather information on the drug’s effect in various populations and to determine any side effects associated with long-term use.
(Additional Resource Information on clinical trials can be found at http://clinicaltrials.gov/)
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