This phase of the testing takes about a year and involves 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, and the duration of its action. This phase normally takes about 2 years. This phase involves 1,000 to 3,000 patients in clinics and hospitals.
Physicians monitor patients closely to determine the efficacy and identify adverse reactions.
This phase lasts about three years. After all of the clinical trials mentioned above are completed, then the company analyzes the data and files an NDA with the FDA if the data successfully demonstrates safety and effectiveness. The NDA is usually about 100,000 pages or more and contains all of the scientific information that the company has gathered. In most cases the time from first submission of an NDA and final FDA approval usually exceeds six months. The average NDA review time for new molecular entities approved in 1992 was 29.9 months.