Clinical testing begins with Phase I studies, which are designed to assess safety, tolerability, pharmacokinetics, and preliminary pharmacodynamic activity of the compound in humans. If these initial tests are favorable, additional, larger Phase II studies are initiated to determine the efficacy of the compound in the affected population, define appropriate dosing for the compound, as well as identify any adverse effects that could limit the compound’s usefulness. If data from the Phase II trials are satisfactory, companies will invest in large-scale Phase III trials to confirm the compound’s efficacy and safety. Upon completion of those trials, if satisfactory, companies submit regulatory filings for marketing approval with the appropriate regulatory agencies around the world to have the product candidate approved for marketing. For the industry as a whole, only one in five of all medicines and vaccines tested in clinical trials are deemed safe and effective enough to be approved for patient use.1
The content on this page was last modified on September 15, 2009.
Merck & Co., Inc., Whitehouse Station, NJ, USA, and Schering-Plough Corporation, Kenilworth, NJ, USA, are now one company. We have combined our global operations under the name Merck & Co., Inc. We are working to update our corporate responsibility Web site to reflect our new, combined, global organization.
1DiMasi JA. Uncertainty in drug development: approval success rates for new drugs. Chapter 20 in Clinical trials and tribulations, 2d edition, revised and expanded.
Cato AE Sutton L Cato A III, editors.New York: Marcel Dekker, 2002:361-77.
