Medline ® Abstracts for References 23,44

BACKGROUND: Dopaminergic medications relieve symptoms of the restless legs syndrome (RLS) but have the potential to cause iatrogenic worsening (augmentation) of RLS with long-term treatment. Pregabalin may be an effective alternative.

METHODS: In this 52-week, randomized, double-blind trial, we assessed efficacy and augmentation in patients with RLS who were treated with pregabalin as compared with placebo and pramipexole. Patients were randomly assigned to receive 52 weeks of treatment with pregabalin at a dose of 300 mg per day or pramipexole at a dose of 0.25 mg or 0.5 mg per day or 12 weeks of placebo followed by 40 weeks of randomly assigned active treatment. The primary analyses involved a comparison of pregabalin and placebo over a period of 12 weeks with use of the International RLS (IRLS) Study Group Rating Scale (on which the score ranges from 0 to 40, with a higher score indicating more severe symptoms), the Clinical Global Impression of Improvement scale (which was used to assess the proportion of patients with symptoms that were "very much improved" or "much improved"), and a comparison of rates of augmentation with pregabalin and pramipexole over a period of 40 or 52 weeks of treatment.

RESULTS: A total of 719 participants received daily treatment, 182 with 300 mg of pregabalin, 178 with 0.25 mg of pramipexole, 180 with 0.5 mg of pramipexole, and 179 with placebo. Over a period of 12 weeks, the improvement (reduction) in mean scores on the IRLS scale was greater, by 4.5 points, among participants receiving pregabalin than among those receiving placebo (P<0.001), and the proportion of patients with symptoms that were very much improved or much improved was also greater with pregabalin than with placebo (71.4% vs. 46.8%, P<0.001). The rate of augmentation over a period of 40 or 52 weeks was significantly lower with pregabalin than with pramipexole at a dose of 0.5 mg (2.1% vs. 7.7%, P=0.001) but not at a dose of 0.25 mg (2.1% vs. 5.3%, P=0.08). There were six cases of suicidal ideation in the group receiving pregabalin, three in the group receiving 0.25 mg of pramipexole, and two in the group receiving 0.5 mg of pramipexole.

CONCLUSIONS: Pregabalin provided significantly improved treatment outcomes as compared with placebo, and augmentation rates were significantly lower with pregabalin than with 0.5 mg of pramipexole. (Funded by Pfizer; ClinicalTrials.gov number, NCT00806026.).

OBJECTIVES: To assess the therapeutic efficacy, required dose, and tolerability of pregabalin in patients with idiopathic restless legs syndrome (RLS).

METHODS: This was a double-blind, placebo-controlled trial with polysomnographic control, providing Class II evidence. Ninety-eight patients underwent a 2-week single-blind period with placebo; 58 were randomized to receive pregabalin or placebo for 12 weeks under a flexible-dose schedule. Endpoints were mean change from baseline in the International Restless Legs Scale (IRLS) total score, Clinical Global Impression (CGI), and RLS-6 scales, as well as changes in periodic limb movements (PLMs) and sleep architecture.

RESULTS: Patients under treatment with pregabalin had a greater improvement in IRLS score than under placebo (63% vs 38.2%; p<0.05). The mean effective dose of pregabalin at the end of treatment was 322.50 mg/day (+/-98.77), although therapeutic effects were already seen at a mean dose of 139 mg/day. Similarly, improvements were observed on the CGI, RLS-6 scale, and the Medical Outcomes Study sleep scale (all p<0.01) when compared to placebo. Treatment with pregabalin also resulted in a reduction of the mean (+/-SD) PLM index (p<0.001). Furthermore, there was a marked improvement in sleep architecture with an increase in slow wave sleep (p<0.01), and decreases in wake after sleep onset and stages 1 and 2 (p<0.05). Pregabalin was generally well-tolerated. Adverse events were mild but common, and included unsteadiness, daytime sleepiness, and headache.

CONCLUSIONS: This study shows significant therapeutic effects of pregabalin on both sensorial and motor symptoms in restless legs syndrome. Treatment with pregabalin was associated with an improvement of sleep architecture and periodic limb movements. Adverse events included unsteadiness and sleepiness and should be screened carefully in the working population, particularly when pregabalin is administered in the afternoon.

CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that pregabalin is effective for the treatment of restless legs syndrome and improves sleep architecture and periodic limb movements in placebo-unresponsive patients.