Long-term open-label study of pramipexole in patients with primary restless legs syndrome

A phase III, open-label, long-term clinical study was performed to evaluate the safety and efficacy of pramipexole in a cohort of 141 Japanese patients with primary restless legs syndrome (RLS). The patients were started on pramipexole 0.25 mg/day and were subsequently maintained on that dose or switched to 0.125, 0.5, or 0.75 mg/day to achieve optimal efficacy and tolerability. The International Restless Legs Syndrome Study Group Rating Scale for restless legs syndrome (IRLS) score improved from 22.3 ± 4.7 at baseline to 11.1 ± 7.7 at week 8 and 4.9 ± 5.9 at week 52. IRLS responders, defined as patients whose IRLS total score decreased by ≥ 50% from baseline, accounted for 67.4% at week 12 and 86.6% at week 52. Over 90% of patients were Clinical Global Impression-global improvement (CGI-I) and Patient Global Impression (PGI) responders. The Pittsburgh Sleep Quality Index (PSQI) score decreased from 7.9 ± 3.1 at baseline to 4.6 ± 2.9 at week 52. Similarly, the Japanese version of the Epworth Sleepiness Scale score decreased from 9.3 ± 5.2 to 4.9 ± 3.8. Baseline IRLS score ≤ 20 was significantly associated with a complete IRLS response in this long-term study. Adverse events were typical of nonergot dopamine agonists, mild in intensity, and decreased in frequency as the study progressed. RLS augmentation was not observed. Pramipexole 0.25–0.75 mg/day is efficacious, safe, and well tolerated in patients with RLS. Pramipexole showed good efficacy, particularly in patients with an IRLS total score < 20.