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Understanding Clinical Trials The FDA Approval Process Important Questions to Ask About Clinical Trials Finding a Clinical Trial

Understanding Clinical Trials


Clinical Trial InfographicIt is an uphill battle to bring one treatment* to the market. Imagine leading an expedition where every step is more difficult than the last. The process began in the laboratory, where it took years sifting through thousands of potential treatments to find a handful that were fit for testing in clinical trials. After successfully crossing the perilous “Funding Valley of Death,”** the trial sponsors are responsible for getting more volunteers over an increasingly difficult terrain with the goal to reach the summit and arrive at one Food and Drug Administration (FDA)-approved product. At the end, it may have taken up to 15 years and more than $1 billion to bring this product to the market.

For a visual summary of this process, please refer to our clinical trial SnapShot (JPEG format) titled “An Uphill Battle.”

What is a clinical trial?

Doctor Discussing Clinical TrialsA clinical trial is a research study conducted with volunteers to find out whether a potential treatment is safe and effective. Today’s clinical trials will lead to new standards of care in the future.

The following is a brief summary of how a potential treatment makes it through the drug development and clinical trial process before it is approved for sale to the public. More detailed descriptions and answers to important questions can be accessed in other sections.

It can take many years for a potential treatment to work its way from the laboratory through rigorous clinical testing and, finally, obtain approval by the Food and Drug Administration (FDA) for sale in the United States.

  • The process begins in the laboratory with basic investigations involving bench-top assays and other techniques, cells, and specially-bred animals (see Basic Research/Drug Development).

  • Next, pre-clinical or translational research moves the successful treatment through further rigorous testing to prepare for clinical testing (see Pre-Clinical/Translational Research).

  • Finally, the treatment is given to human volunteers enrolled in clinical trials that typically proceed through a succession of three phases (see Phase 1, Phase 2, and Phase 3 Clinical Trials).

These trials are used to determine the safety and effectiveness of the intervention on progressively larger numbers of people. Normally, if the results are positive in the first three phases—depending on the measurement of success defined at the beginning of each phase—the therapy will proceed to the FDA for review on whether it is deemed to be safe and effective for distribution to the public.

Once approved, the sponsor will manufacture the treatment on a large scale for distribution in the United States (see FDA Review/Manufacturing). Once on the market, the FDA monitors for serious adverse events, and additional clinical trials may be requested by the FDA or undertaken voluntarily by the sponsor company (see Phase 4 Clinical Trial/Post-Market Surveillance/Report Adverse Events). The data gathering, analysis, and reporting that are necessary to complete these trials can take several years or more. In fact, it can take up to 15 years and more than $1 billion to bring one FDA-approved intervention to the market (please refer to the clinical trial SnapShot titled “An Uphill Battle”).

People with a medical condition or healthy individuals may consider participating in clinical trials. Each trial has its own protocol, or set of guidelines, and volunteers first must meet certain criteria to qualify for enrollment. Before making a decision and giving their informed consent, each person should seek as much information as possible about the trial, and think seriously about the benefits and risks of volunteering. Benefits to volunteering are actively becoming involved in your own healthcare and the satisfaction of helping others with the medical condition studied in the clinical trial (if you are not affected). However, there may be side effects or the treatments may not be effective, and participation will require a time commitment.




Treatment: Although we are using the word "treatment," clinical trials also involve medical research studies in which people participate as volunteers to test new methods of prevention, screening, and diagnosis of disease.


"Funding Valley of Death": Many promising potential drugs, devices, or other potential treatments are never tested in clinical trials due to lack of funding or other business difficulties. In many cases, further financial support or partnerships are needed to help "bridge the gap" across the "Funding Valley of Death" to begin Phase 1 Clinical Trials.

Sources of Information

U.S. Food and Drug Administration (FDA); National Institutes of Health (NIH); Center for Information & Study on Clinical Research Participation (CISCRP); Pharmaceutical Research and Manufacturers of America (PhRMA); Tufts Center for the Study of Drug Development [Updated Outlook 2010 and original referenced paper (DiMasi, Joseph A., Ronald W. Hansen and Henry G. Grabowski (2003) “The Price of Innovation: New Estimates of Drug Development Costs,” Journal of Health Economics 22(2):151-85, March)]; and a paper comparing the costs of different studies (Morgan, Steve, et al. “The cost of drug development: A systematic review” Health Policy 100 (2011) 4–17).

Last Review: 01/17/14