The Phases of Clinical Trials in U.S. Federal Drug Administration New Drug Approval Process
Ertz, Natalie M.1,2 and Cantafio, Nina A.2
1School of Life Sciences, Arizona State University, Tempe, AZ; 2TGEN Clinical Research Services at Scottsdale Clinical Research Institute, Inc.
Clinical trials are essential for medical advancements including new drug development and discovery. In fact, they are also a mandatory procedure by the Food and Drug Administration (FDA) before releasing a new product into the market in the United States. The objective in any treatment trial is to investigate a potentially advantageous drug for its safety and effectiveness. There are four phases of clinical trials that differ in number of participants and specific inquiry. Phase I begins after pre-clinical investigation in animals deems the drug appropriate for trial in humans. This phase introduces the drug into humans for the first time, usually in a small group of people. The aims of this phase are to determine metabolic and pharmacologic actions, side effects with increasing dosage, and early effectiveness evidence of the investigational drug. The Phase II objective is to monitor short-term side-effects, risks, and drug effectiveness. By Phase III there can be several thousand participants. It is intended to obtain further information that is ultimately used to determine the overall benefit-risk relationship. Additionally, phase III compares the investigational drug to the current standard through randomization. These trials provide the evidence drug sponsors use in a New Drug Application that the FDA reviews to consider approval for marketing in the United States. A drug sponsor may be required to hold a phase IV trial. Phase IV trials are initiated after the FDA has approved the drug for marketing and is designed to obtain additional information regarding safety, effectiveness, and optimal use.