ABSTRACT
The drug development process is both long and complex. The average time from discovery to approval has been estimated to be 10 years. Drug development proceeds through four stages: preclinical studies in animals, and phase I, phase II, and phase III clinical studies in humans. Phase I studies are small studies performed in healthy volunteers (and sometimes in subjects with the target disease) to gain basic safety and pharmacological information. Phase II studies are larger, and include subjects with the target disease. Phase II studies provide additional safety data and some efficacy data. These studies are often used to establish the optimal dose or doses for examination in a phase III study. Phase III studies (often referred to as pivotal studies) serve as the primary basis for a drug’s marketing approval. These studies are usually large, randomized, controlled
trials performed in subjects with the target disease, and typically involve several hundred to several thousand patients.
