how long do clinical trials last
Prevention clinical trials will frequently last 10 to 20 years in order to evaluate the long-term implications of lifestyle changes such as exercise or diet. A more common span is three to seven years for new drugs or devices. However long a clinical trial lasts, a clinical trial may have several stages. Clinical trials for new drugs proceed through four distinct phases, starting with a small group (fewer than 100) of patients and progressing to larger trials and usually further trials after the drug is approved.