How are drugs approved? Part 3. The stages of drug development

The first article of this series on the drug development process described the historical evolution of the U.S. Food and Drug Administration (FDA), and last month's article reviewed the ethical foundations of clinical research. Before a new drug is marketed, a sequence of preclinical investigations and three phases of clinical studies are conducted. This drug development process involves the FDA, pharmaceutical companies (sponsors), clinical investigators, and institutional review boards. This article further describes this aspect of the drug development process.