RESEARCH

People count on us to make medicines and vaccines that have well documented safety and effectiveness profiles and offer meaningful value to patients. Clinical trials (also known as clinical studies) are a critical step in this process.

Before they may receive approval for use, medicine and vaccine candidates undergo rigorous and systematic testing in patient volunteers. This process is designed to evaluate whether a new candidate should be approved for use in the broader population.

Each clinical trial is designed to answer certain research questions. They follow strict, predefined protocols are designed to ensure safe and accurate results. Each phase has a different purpose in the development of a medicine or vaccine:

• Phase I: The medicine is tested in a small group (20-100) of healthy volunteers - often in a hospital setting - to determine its safety profile, including the safe dose range. Pharmacokinetic studies examine how a drug is absorbed, distributed, metabolized and excreted, as well as the duration of its action. Phase I studies can take from six months to one year to complete.
• Phase II: Placebo-controlled trials involving approximately 100 to 500 volunteer patients who have the disease being studied. The goal of this phase is to establish the "proof of concept" - i.e., the medicine effectively treats the disease. Researchers continue to evaluate the drug's safety and look for side effects, and determine optimal dose strength and schedule (e.g., once or twice daily). Phase II studies can take from six months from one year to complete.
• Phase III: The medicine is tested in large, randomized, placebo-controlled trials with much larger numbers of patient volunteers - from 1,000 to 5,000, in hospitals, clinics and/or physician offices - to generate statistically significant data. Researchers closely monitor patients at regular intervals to confirm that the drug is effective and identify side effects (also called adverse events). Phase III studies can take from one to four years to complete, depending on the disease, length of the study, and the number of volunteers.
  
• On-going studies: After a drug or treatment has been approved by the appropriate government and regulatory agencies and is being marketed, we continue to study its safety and effectiveness over a longer period of time and in a larger number of people. We may also continue to study some of our marketed products for new indications. Thousands of people usually participate in on-going trials.

At Merck, 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.

Note: Merck and Schering-Plough have combined our global operations under the name Merck & Co., Inc. We are working to update our entries in these two online registries to reflect this change. In the meantime, you can search for information about our ongoing clinical trials by using both "Merck" and "Schering-Plough" as search terms.

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