Before they may receive approval for use, medicine and vaccine candidates undergo rigorous and systematic testing in volunteers. This process is designed to evaluate whether a new product should be approved for use in the broader population.
Each clinical trial is designed to answer certain research questions. They follow strict, predefined protocols to ensure safe and accurate results. Each phase has a different purpose in the development of a medicine or vaccine:
- Phase I: Researchers test an experimental drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine an appropriate dosage, trace what happens to the compound in the body, and begin to identify side effects.
- Phase II: The drug or treatment being studied is given to a larger group of people with the disease (100-300) to obtain preliminary evidence of an effect and to further evaluate its safety. If there is evidence of an effect and the risks are considered acceptable, the drug may move to the next stage.
- Phase III: This phase of trial tests a drug candidate in a larger number of people with the disease (1,000-3,000), further testing its effectiveness and monitoring for side effects. In some cases this will be compared to a treatment standard, if one is already available.
- Phase IV: After a drug or treatment has been approved by the appropriate government and regulatory agencies and is being marketed, we study its safety and effectiveness over a longer period of time and in a larger number of people. We also continue to study some of our marketed products for new indications. Thousands of people usually participate in Phase IV trials.
At MSD, our clinical trials are designed, conducted and monitored in adherence to the same standards, whether they take place in the United States or elsewhere around the world. In conducting clinical trials, we also adhere to the guidelines of The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use.
Please visit our clinical trials website http://www.merck.com/clinical-trials to learn more about our studies.