Restless legs syndrome (RLS) affects 2 to 15 percent of the population. The symptoms of RLS contribute to disturbed sleep and profound daytime sleepiness. In recent open-labeled trials, pergolide, a dopamine-receptor agonist, has shown efficacy in treating RLS. Earley and colleagues studied the effectiveness of pergolide in the management of RLS.

Sixteen patients who met the criteria for RLS as outlined by the International RLS Study Group and who had a minimum of 15 periodic limb movements of sleep per hour on standard polysomnography were included in the randomized, double-blind, placebo-controlled study. Patients were assigned to treatment with pergolide or placebo and were permitted to increase the dosage during the 14-day study period until the benefits of the medication were believed to be adequate, the maximum dosage was reached or adverse effects occurred.

The final dosage of pergolide ranged from 0.1 mg to 0.65 mg per day. Subjective patient assessment as well as objective sleep data were used to measure efficacy. The primary outcome measures were the number of periodic limb movements of sleep per hour (obtained by all-night polysomnography), percentage of sleep efficiency (the amount of time sleeping divided by the amount of time in bed), number of hours per day with RLS symptoms and global improvement score (both from subjective patient assessment).

The mean sleep efficiency for patients in the pergolide group rose from 61 percent to 79 percent. The average hourly number of periodic limb movements of sleep dropped from 48.9 to 14.5. The average number of hours with RLS symptoms decreased from 7.0 hours per day to 1.8 hours per day. The average global improvement scale was 61 percent for pergolide compared with 19 percent for placebo. The placebo group showed no statistically significant change from baseline for any of the four outcome variables.

The authors conclude that pergolide helps improve both subjective and objective measures of RLS. Patients who used the drug had increased sleep efficiency and decreased periodic limb movements of sleep while displaying no worsening of symptoms in the hours preceding the next dose.