Table 3.

NIH clinical trial phases for human subject research

“Biomedical clinical trials of an experimental drug, treatment, device, or behavioral intervention may proceed through four phases” [18]
Phase 1	Tests a new intervention in a small group of human subjects for the first time to evaluate efficacy and safety.
Phase 2	Tests the efficacy of a new intervention in a larger group (usually several hundred) to further evaluate efficacy and safety.
Phase 3	Compares a new intervention to standard or to other experimental interventions in large groups (several hundred to thousands) to determine efficacy and to monitor and collect data on adverse effects.
Phase 4	Assesses after-market effectiveness in the general population and collects data on any adverse effects associated with widespread use.