Table 2.

FDA clinical study phases for new drug applications

“The new drug application is the vehicle through which drug sponsors formally propose that the FDA approve a new pharmaceutical for sale in the United States” [17]
Phase 1	Emphasizes the assessment of safety - how a new drug is metabolized and excreted, how a drug should be given, how often, at what dose. It is usually conducted with a small number of healthy volunteers.
Phase 2	Continues to test safety and begins to evaluate how well a drug works by comparing it with a different treatment, usually a placebo or another drug. Conducted in a larger sample.
Phase 3	Tests the efficacy of a new drug in comparison to the current standard, evaluates dosages and overall risk-benefit of the drug. Conducted in a large numbers of volunteers.
Phase 4	Studies post-approval use of a drug if the FDA judges the need to gather population data on drug safety.