Pramipexole in the treatment of restless legs syndrome: a follow-up study

The restless legs syndrome (RLS) is a condition characterized by unpleasant limb sensations occurring at rest and associated with an irresistible urge to move. Several treatments are used to treat RLS including benzodiazepines, opioids, dopaminergic agents, clonidine and anticonvulsant drugs such as carbamazepine and gabapentine. Dopaminergic agents are now considered the treatment of choice for RLS. Levodopa is effective in treating RLS; however, several patients treated with levodopa at bedtime developed morning or late afternoon restlessness. Recently, more attention has been paid to dopamine receptor agonists. Ergoline derivatives, bromocriptine and pergolide were found effective, but require concomitant administration of domperidone, a peripheral dopamine antagonist. In a recent study, we studied the efficacy and innocuity of pramipexole, a new dopamine agonist with a higher affinity for the D3 receptor subtype of the D2 family, in a double-blind, placebo-controlled, randomized trial. Pramipexole had major effects on RLS symptoms without severe side-effects. The present study aimed to assess the long-term efficacy of pramipexole. Seven patients were treated with the drug for a mean follow-up duration of 7.8 months. Treatment was started at a dosage of 0.25 mg, and progressively increased until the optimal therapeutic effect was obtained. Home questionnaires were completed for 7 consecutive days, after one month and after a mean of 7.8 months of treatment with pramipexole, assessing leg restlessness during the daytime, in the evening, at bedtime and during the night. There was no evidence of a decrease in the therapeutic effect of pramipexole in these patients, even 7.8 months after the initiation of treatment. The optimal dosage was 0.25 mg for one patient, 0.5 mg for five patients and 0.75 mg for one patient. While there was a progressive increase in severity of leg restlessness from daytime to nighttime before treatment, a suppression of leg restlessness was observed throughout the 24 h with a single dose of pramipexole at bedtime. The remarkable efficacy of pramipexole raises the possibility that the D3 receptors of the mesolimbic system may be more specifically involved in the physiopathology of RLS.