Trial Phases for Investigating Drugs and Treatments

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Trial Phases for Investigating Drugs and Treatments

FDA-Approved Medications

Experimental Oral Medications

Experimental Monoclonal Antibody Medications

Other Therapies Being Studied

New Directions in MS Research

A Phase I clinical trial tests for safety in humans, with typically less than 100 healthy volunteers. Investigators observe how the human body responds to the medication to determine safe doses and related side effects. Phase I trials are referred to as "open label" and "unblinded," because everyone - the patient, medical staff, and investigators - knows the drug and dose that each participant is receiving. Phase I trials can take several months to one year to complete.

Phase II clinical trials, which look at safety and efficacy (effectiveness), typically run for several months to two years. In this phase, approximately 100 to 300 people with the disorder (in this case, MS) are given either the active drug or a "placebo" (a medication that looks the same as the drug being tested, but has no active ingredients). Phase II studies are often "double-blinded," meaning that the participants, medical staff, and investigators are not told who is receiving the drug and who is receiving the placebo. These studies are also "randomized," so that participants are assigned to treatment groups (or "treatment arms") based on chance.

Roughly one-third of experimental medications for MS reach the Phase III clinical trial level. These trials can take several years to complete and involve 1,000 to 3,000 participants at many different medical locations. These studies are randomized, placebo-controlled, and doubleblinded. They are designed to provide more information on a drug's safety and efficacy, as well as additional benefits, side effects, and adverse reactions. Upon completion, a data analysis is performed. If the results are favorable, an application for approval is submitted to the Food and Drug Administration (FDA), whose panel reviews the results and recommends approval if it finds the treatment to be beneficial and safe.

Phase IV clinical trials are conducted after a drug has been approved. Participants are enrolled to further monitor safety and side effects, while evaluating long-term efficacy.

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