GlaxoSmithKline has become the first company to win approval in the USA for a drug to treat restless legs syndrome, a distressing movement and sleep disorder that can severely affect quality of life.

GSK’s Requip (ropinirole), a dopamine agonist already approved for the treatment of Parkinson’s disease, has won approval in the US for use in patients with moderate-to-severe RLS. The approval gives GSK a head start in this so far largely untapped market, ahead of rival Boehringer Ingelheim. The latter’s own dopamine agonist, Sifrol/Mirapex (pramipexole), reacquired from Pfizer last year [[21/10/04i]], is scheduled to be filed for approval in RLS later this year. At present, there are no approved treatments for RLS with the exception of some older products registered in Germany and Switzerland.

Pfizer halted the clinical development of its own RLS and Parkinson’s disease candidate, sumanirole, last year after disappointing results from clinical studies which it said failed to significantly distinguish the agent from currently-available therapies [[22/07/04b]].

First described in the early 1940s by eminent neurologist Karl Ekbom, RLS is characterised by a compelling urge to move the legs and by uncomfortable or sometimes painful sensations in the legs often described as creeping-crawling, tingling, pulling or tightening.

Last year, a survey published in the journal Sleep Medicine suggested the average prevalence of RLS in the population of five western countries was 3.4%, led by the USA (5.8%) and closely followed by the UK (5.6%). The other three countries surveyed – Spain, France and Germany, had rates of 1.9%, 2.1% and 3.7%, respectively.