Comparison of pregabalin with pramipexole for restless legs syndrome

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.

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.

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.

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.).