Clinical Trials In FDA Drug Approval Process
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Role Of Clinical Trials In The FDA Drug Approval Process

Last time, I published the second in a brief series of blog posts designed to provide insight into why prescription drugs in the U.S. cost as much as they do. The series is focused on explaining the FDA drug approval process in layman’s terms. My previous post focused on the first stage in the process, the preclinical stage. Today’s post puts the spotlight on the clinical stage, which tends to span several years.

Phase I Clinical Trials

Approximately 20-80 healthy volunteers participate in a phase I clinical trial. This phase emphasizes safety and the goal is to determine the drug’s most frequent side effects, as well as how the drug is metabolized and excreted.

Phase II Clinical Trials

Hundreds of patients participate in a phase II clinical trial. This phase emphasizes effectiveness and the goal is to obtain preliminary data on whether the drug works in people who have a certain disease or condition. For controlled clinical trials, patients receiving the drugs are compared to similar patients receiving a different treatment, usually a placebo or a different drug. Safety continues to be evaluated and short-term side effects are studied. At the end of this phase, the FDA and sponsor discuss how large-scale studies in a phase III clinical trial will be conducted.

Phase III Clinical Trials

Thousands of patients participate in a phase III clinical trial. The purpose of this phase is to gather more information about safety and effectiveness, study different populations and different dosages, and explore the use of the drug in combination with other drugs.

Once an investigational drug has successfully advanced through all of the required trials, it advances to the third stage: new drug application (NDA) review. Check back next time to learn what happens in the NDA review stage. In the meantime, I recommend downloading our latest guide by filling out the form below.

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