What Is a Clinical Trial?
A clinical trial is a
research study that involves people to evaluate the effectiveness of a
therapeutic, invasive, surgical or care management intervention through the
process of randomization assigning each subject to treatment group by chance in
order to balance known and unknown treatment variables that may influence the
disease process and response to treatment.
Phases
Phase I
In a phase I clinical study, the investigational new drug is tested for the first time in
human subjects for the purpose of evaluating the safety of the drug. The safety profile of the investigational agent is determined by monitoring the metabolism and pharmacologic actions of
the drug and determining the maximum tolerated dose in a small population of
subjects (20 to 80). (21 CRF 312.21(a)
Phase II
In a phase II clinical trial the purpose of the study is to evaluate the effectiveness and safety of the investigational drug in a larger group of patients (typically 100 to
300) by determining the most effective tolerated dose and monitoring common side effects and risks associated with the drug. (21 CRF 312.21(b)
Phase III
In a phase III clinical trial the investigational drug has demonstrated effectiveness and the
main purpose is to obtain additional information regarding the drug’s safety
and effectiveness that is needed for evaluating the risk and benefit of the
drug which is necessary for the labeling and marking of the drug. Typically
phase III trials are large (300 to 1000 patients) randomized, multi-center
trials. (21 CRF 312.21(c)
Phase IV
In a phase IV clinical trial the study is conducted after the product has been approved by the FDA for the purpose to gain additional information about the drugs risks, benefits, optimal use and evaluation of the drug in different patient populations. (21 CRF 314.80)
