Once researchers have completed a rigorous screening and preclinical testing process, the company files an Investigational New Drug (IND) application with the U.S. Food and Drug Administration (FDA). This application allows the investigational drug to be tested in human volunteers in clinical trials. A clinical trial is a carefully designed study which tests the benefits and risks of a specific medical treatment or intervention, such as a new drug or a behavior change (e.g., diet).
Every clinical trial is led by a principal investigator, who is usually a doctor, along with a team of nurses and others researchers. The FDA requires a multi-phase clinical trials process to be completed before deciding if the medicine under investigation is safe and effective for a broader patient population. Usually, these number of human volunteers in the trial increases as the treatment moves through these phases. That is why innovative medicines cannot be developed without the help of volunteers who participate in clinical trials.