Efficacy and safety of pramipexole in Japanese patients with primary restless legs syndrome: A polysomnographic randomized, double-blind, placebo-controlled study

Abstract

Objective To evaluate the efficacy of pramipexole on polysomnographic measures, patient ratings and a clinical rating in Japanese patients with primary restless legs syndrome (RLS). Methods Patients with moderate to severe RLS having periodic limb movements in bed index (PLMI) ⩾ 5 were randomly assigned to receive pramipexole or placebo in a 6-week, double-blind, placebo-controlled study with forced titration from 0.125 to 0.75 mg/day. Both polysomnography (PSG) and the suggested immobilization test (SIT) were performed at baseline and 6 weeks after starting treatment. Results The analysis of covariance of log-transformed PLMI showed that the adjusted means at the end of study were significantly smaller in the pramipexole group than in the placebo group ( p = 0.0019). In all patients, variables on SIT did not show any differences between the two groups, whereas a significant improvement was shown in the pramipexole group compared with the placebo group for patients with a SIT-PLM index at baseline ⩾ 15. Pramipexole group showed a significant reduction in the International Restless Legs Syndrome Study Group rating scale (IRLS; p = 0.0005), a significant improvement in both Patient Global Impression (PGI; p < 0.0001) and Clinical Global Impressions (CGI-I; p = 0.0488), and a significantly greater mean reduction in the Pittsburgh Sleep Quality Index (PSQI; p = 0.0016), when compared with those of placebo group at week 6. Conclusions Pramipexole is highly efficacious in the reduction of PLMI and in the improvement of subjective severity of RLS and subjective sleep disturbance caused by the disorder.