Clinical Trial Phases
Clinical trials are conducted in phases to obtain specific information about the treatment or experimental drug.
Phase I Trials
A small number of participants are used to test an investigational drug or treatment. The main focus is to determine the safety of the drug in humans. They evaluate the safe dose range and identify possible side effects from the drug/treatment.
Phase II Trials
After completing the Phase I trials, the information is used to treat a slightly larger number of participants. Phase II uses the information gathered from Phase I to further evaluate the safety and effectiveness of the drug/treatment.
Phase III Trials
The experimental treatment is given to a large group of participants in a variety of clinical settings to evaluate its safety, effectiveness and to monitor the side effects.
Phase IV Trials
Once the drug has been approved by the FDA, this is when post marketing studies are conducted to continue to gain more information about the benefits and safety of the drug.