A clinical trial is a study conducted to determine the efficacy of behavioral, medical and surgical interventions. Scientists also use clinical trials to evaluate the safety of new drugs and medical devices and detect and prevent illnesses. Usually, scientists test animals first, and if the results are favorable, the FDA approves the treatment for human testing in clinical trials.
In clinical trials, scientists compare the new treatment's value to the standard treatment's value. A new treatment is beneficial if it has less dangerous side effects or higher efficacy than the standard treatment.
There are four phases of clinical trials. An intervention must pass the previous phase to move on to the next.
- Phase I trial: tests a small group of 20-80 healthy individuals to establish side effects, safety and optimal dosage.
- Phase II trial: tests 100-300 individuals to determine effectiveness on certain illnesses. This phase can also test the safety and usually lasts years.
- Phase III trial: tests the safety and effectiveness in hundreds to 3,000 individuals while looking at dosages, populations and drug interactions.
- Phase IV trial: tests the safety and effectiveness in large, diverse populations after receiving FDA approval.