The purpose of clinical trials is to collect data about the safety and efficacy of new drug and device development. There are several steps and stages of approval in the clinical trials process a drug or device must go through before it can be sold in the consumer market. If it fails any of the stages, it may not be approved. Since there are no devices used for P/P, this page will focus on treatments.
Drug testing begins with extensive laboratory research that can last years. During this time, experiments in animals and human cells will occur. If this initial laboratory research is successful, researches send the data to the United States Food and Drug Administration (FDA) for approval to continue research and testing in humans. If approved, human testing of experimental drugs begins. This testing is usually done in five phases (Phase 0-IV) with each considered a separate trial. After each phase is completed, investigators must submit their data back to the FDA for approval before continuing to the next phase.
Human Clinical Trial Phases
Phase 0 exploratory studies involve very limited human exposure to the drug, with no therapeutic or diagnostic goals (for example, screening studies, microdose studies).
Phase I studies assess the safety of a drug and is the initial phase of testing. This phase can take several months to complete, usually including a 20-100 healthy volunteers who are typically paid for their participation. This phase determines the effects of the drug on humans including how it is absorbed, metabolized, and excreted. This phase also investigates any side effects that occur as dosage levels are increased.
Phase II studies test the efficacy of a drug. This second phase of testing can last from several months to two years. It can involve several hundred patients. Most phase II studies are randomized trials where one group of patients receives the experimental drug, while a second “control” group receives a standard treatment, or placebo. These studies are “blinded” meaning neither the patients nor the researchers know who has received the experimental drug. This allows investigators to provide the pharmaceutical company and the FDA with comparative information about the relative safety and effectiveness of the new drug.
Phase III studies involve randomized and blind testing in several hundred to several thousand patients. This large-scale testing can last several years and provides the pharmaceutical company and the FDA with a thorough understanding of the effectiveness of the drug, its benefits, and the range of possible adverse reactions. Once Phase III is complete, a pharmaceutical company can request FDA approval for marketing the drug.
Phase IV studies (Post Marketing Surveillance Trials) are conducted after a drug has been approved for consumer sale. Pharmaceutical companies have several objectives at this stage: (1) to compare a drug with other drugs already in the market; (2) to monitor a drug’s long-term effectiveness and impact on a patient’s quality of life; and (3) to determine the cost-effectiveness of a drug therapy relative to other traditional and new therapies. Phase IV studies can result in a drug being taken off the market or restrictions of use could be placed on the product depending on the findings in the study.
Participating in a Clinical Trial
For detailed information and an FAQ about participating in clinical trials, please visit Should I Volunteer? And how?
Funding Clinical Trials
Funding for clinical research comes from the federal government (e.g., National Institutes of Health, Department of Defense, Department of Veteran’s Affairs), private industry (e.g., pharmaceutical and biotech companies), medical institutions, and foundations.