FDA Approves Mirapex for Moderate to Severe Restless Legs Syndrome

On November 7, 2006, the U.S. Food and Drug Administration approved the use of pramipexole (brand name, Mirapex) for the treatment of moderate to severe restless legs syndrome (RLS). The drug was already approved for the treatment of Parkinson’s disease.

What is Restless Legs Syndrome?: A number of people with fibromyalgia also suffer with restless legs syndrome – a sensory disorder that causes an almost irresistible urge to move the legs. This urge to move is usually due to unpleasant feelings in the legs that have been described as creeping, crawling, tingling or burning. RLS occurs most often when the person is trying to rest. Moving the legs seems to ease the feelings, but only temporarily.

Why it Was Approved: The data upon which the FDA based its decision were the results of four randomized, double-blind placebo-controlled trials to test the efficacy of Mirapex tablets in the treatment of restless legs syndrome, presented by Boehringer Ingelheim Pharmaceuticals, Inc., the drug's manufacturer. The trials included approximately 1,000 patients with moderate to severe RLS.

Patients were randomized to receive either pramipexole or the placebo once a day, two to three hours before bedtime. The pramipexole was gradually increased from 0.125 mg to 0.25mg, 0.5 mg, or 0.75 mg. Two-thirds of the participants were women who ranged in age from 18 to 81, with an average age of 55 years. The length of time participants had RLS ranged from zero to 56 years, with an average duration of 4.6 years.

Clinical Trial Results: In a 12-week study of 344 patients, those receiving the pramipexole, compared to the placebo, showed significant decreases in severity of sensory and motor symptoms, sleep disturbance, daytime sleepiness and impact on activities of daily living and mood. In a nine-month study, patients who had responded positively to six months of treatment with pramipexole were randomized to receive either a placebo or a continuation of the pramipexole for the next three months. By the end of that time, 85 percent of the placebo group had treatment failure compared to only 21 percent of the pramipexole group.

Side Effects: The most common side effects related to pramipexole as prescribed for RLS are nausea and sleepiness. Additional possible side effects include headache, fatigue, and insomnia.

Precautions: Do not drive a car, operate a machine, or do anything that needs you to be alert until you know how Mirapex affects you. Be sure to tell your doctor right away if you fall asleep while you are in the middle of an activity such as talking with people or eating.