How Medications Become FDA-Approved

Every drug that is sold to consumers, either by prescription or over-the-counter, must first be tested for safety and efficacy.

Before a drug can be tested in people, the drug company or sponsor performs laboratory and animal tests to discover how the drug works and whether it's likely to be safe and work well in humans.

Next, a series of tests in people is conducted to determine if the drug is safe when used to treat a disease and whether it provides a real health benefit.

There are three main “phases” to a clinical trial research. Each phase has a different purpose.

  • Phase I: assesses the safety of an investigational drug. This first phase usually takes months to complete. It involves a small number of research subjects, usually about 20 to 80. The purpose of this phase is to identify any side effects produced by a drug, how it is metabolized in the body and appropriate dose to give study subjects in later trials. They are usually performed on healthy volunteers first and later on patients with the disease or condition the researchers are hoping to treat.
  • Phase II: assesses the safety and efficacy of an investigational drug. This phase will typically last 1 - 2 years and involves 100 to 300 patients. Most Phase II studies are “randomized,” which means that a patient is randomly assigned to either receive the investigational drug or another drug that is currently approved for the disease under the study. Some Phase II studies might involve a “placebo” arm, where no treatment is given to a patient.
  • Phase III: provides researchers a more thorough understanding of the investigational drug to determine its effectiveness in treating the disease under the study. This phase typically lasts for two or more years and enrolls a very large number of patients (hundreds to thousands).

Once all Phase III studies are completed, the drug company takes its data to the FDA for consideration of approval for marketing.