The IND becomes effective if FDA does not disapprove it within 30 days. These tests involve about 20 to 80 normal, healthy volunteers. The tests study a drug's safety profile, including the safe dosage range. The studies also determine how a drug is absorbed, distributed, metabolized, and excreted as well as the duration of its action. This phase usually involves 1,000 to 3,000 patients in clinics and hospitals.
Physicians monitor patients closely to confirm efficacy and identify adverse events.
Following the completion of all three phases of clinical trials, a company analyzes all of the data and files an NDA with FDA if the data success-fully demonstrate both safety and effectiveness. The NDA contains all of the scientific information that the company has gathered. NDAs typically run 100,000 pages or more. The average NDA review time for new molecular entities approved in 1997 was 16.2 months. Once FDA approves an NDA, the new medicine becomes available for physicians to prescribe.