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Restless legs syndrome (RLS) is a disorder characterized by an intense and irresistible urge to move the legs, usually associated with sensory complaints and motor restlessness. The symptoms worsen at rest, increase in severity in the evening or at night, and are relieved by movements [1]. The prevalence of RLS is around 5% [2], although the condition is probably underdiagnosed. It can be idiopathic, usually familial, or secondary to other medical conditions, such as uremia, iron deficiency, and peripheral neuropathy [3].
There are several evidences pointing to a pivotal role of the dopaminergic system in the genesis of RLS. Levodopa and dopamine agonists, such as pramipexole [3] and pergolide [4], are effective in the treatment of RLS, whereas dopamine antagonists often worsen the symptoms [2]. Besides this pharmacological evidence of a dopaminergic abnormality in RLS, functional neuroimaging studies suggest an involvement of the dopaminergic system of the basal ganglia in this disorder [5,6].
Zolpidem is a short-acting nonbenzodiazepine GABAergic drug selective to the BZ1 subtype receptor. A high density of zolpidem-- binding sites in the basal ganglia has been reported [7]. Recent reports describe a favorable action of this drug in Parkinson's disease [8] and progressive supranuclear palsy [9], with improvement of motor symptoms in both conditions.
Because of this effect in disorders of the dopaminergic system, we investigated the effectiveness of zolpidem in patients with RLS refractory to other treatment strategies. A prospective, noncontrolled, open-label study with 8 patients with RLS [1] who were unresponsive to or could not tolerate L-dopa...