UCLA Neurological Rehabilitation and Research Program

A Phase 1 trial evaluates the safety of a test drug or other rehabilitation therapy in a small population. Goals included testing the mechanism of action, identifying potential toxicity and side effects, and establishing dosage range for future trials. In a Phase II trial, safety is still the most important issue, but efficacy becomes the more central criterion and the size of the test group increases. Phase III marks the final pre-marketing step; if testing in a large group of patients (300-3000) finds that a product or rehabilitation therapy managed to prove the desired medical or scientific endpoint(s), and was safe to use, the results will be submitted to the FDA for approval of the drug's use in the general population. Side effects are monitored and the benefits of use are compared to other treatments. It is important to realize that this stepwise process through gradually larger and more complex protocols protects the patients, improves the understanding of the medicine being tested, and allows the sponsor to value it.

After a drug is approved by the FDA, it can be marketed. Postmarketing safety surveillane falls into Phase IV category. These sorts of trials continue the evaluation of risks and benefits associated with the therapy after it has been made widely available. For the interested, an excellent review of this material is available on the web at www.clinicaltrials.gov.