Phases of clinical trials

Clinical trials generate the highest level of scientific evidence to advance clinical practice by identifying interventions that are safe and effective in human subjects. Interventions include diagnostic tests, medicines, therapies, and procedures. The phases of clinical trials, Phase 0 to Phase IV, highlight the stepwise evaluation of an intervention's safety and efficacy in a controlled environment. Phase 0 trials determine initial pharmacologic activity. Phase I trials establish safety and Phase II trials assess efficacy in addition to safety. Phase III trials compare interventions with current the standard of care. Phase IV trials implement post-marketing surveillance of long-term benefits and toxicities.