Boehringer Ingelheim announced that the US Food and Drug Administration (FDA) has approved pramipexole, a non-ergot dopamine agonist, for the treatment of moderate to severe primary Restless Legs Syndrome (RLS). This is an important milestone for pramipexole (Mirapexin/Sifrol/Mirapex), which was already approved throughout the European Union in April 2006 for this second indication.

Millions of patients worldwide are affected by RLS, a debilitating neurological condition. Restless Legs Syndrome is characterised by a compelling urge to move the legs, usually associated with uncomfortable or sometimes painful sensations in the legs, with symptoms being worse at night and while at rest.2 restless legs syndrome patients may also experience daytime tiredness, mood disturbance, and inability to perform daily activities, such as travelling long distances or going to the cinema 2,3,6

"Often patients don't realise that they have an underlying treatable medical condition that is causing these symptoms as well as sleep disturbance. With pramipexole, physicians now have another option to help manage their patients' RLS symptoms," said professor John W. Winkelman, MD, PhD, medical director of the sleep health center of Brigham and Women's Hospital, Boston, Massachusetts, USA.

The FDA approval was based on safety and efficacy data from four randomised, double blind, placebo-controlled clinical trials. These studies involved approximately 1,000 patients with primary moderate-to-severe RLS who were administered pramipexole (0.125mg, 0.25mg, 0.5mg and 0.75mg) or placebo once daily, 2-3 hours before going to bed. In clinical studies, patients treated with pramipexole experienced statistically and clinically significant improvements in short- and long-term efficacy versus placebo. In three clinical studies, the mean change from baseline in total International RLS Rating (IRLS) scores for patients treated with pramipexole demonstrated a statistically significant greater improvement compared with placebo-treated patients. In a fourth study, efficacy was sustained with pramipexole over a period of nine months, including a six-month open label treatment period followed by a 12-week placebo-controlled withdrawal period.1,4

"Building on nearly a decade of worldwide experience for pramipexole in the treatment of Parkinson's disease, we are pleased that the FDA has also approved this second indication. Pramipexole will now be available to the millions of people across the globe living with RLS, helping them to enjoy a better quality of life," said Dr. Andreas Barner, vice chairman of the board of managing directors and responsible for the Corporate Board Division Pharmaceutical Research, Development and Medicine at Boehringer Ingelheim.

Restless Legs Syndrome is a neurological disorder characterised by an uncontrollable urge to move the legs, usually accompanied by unpleasant and sometimes painful sensations in the legs. Restless Legs Syndrome affects up to ten per cent of the population worldwide aged between 30 and 79 years5 and around one-third of sufferers experience symptoms more than twice weekly causing moderate to severe distress.2 The motor-restlessness worsens during the evening and night causing difficulty initiating and maintaining sleep. The sleep disruption can lead to excessive daytime sleepiness and compromise work performance. Restless Legs Syndrome also has considerable impact on social activities that require immobility.

Pramipexole (known in Europe under the trade names Mirapexin and Sifrol and in the USA as Mirapex is a compound from Boehringer Ingelheim research first approved in 1997 for the treatment of the signs and symptoms of idiopathic Parkinson`s disease, as monotherapy or in combination with levodopa.

Pramipexole was approved in April 2006 throughout the European Union for the symptomatic treatment of moderate to severe idiopathic Restless Legs Syndrome (RLS), in addition to other countries such as Australia, Brazil, Canada, Mexico, USA and others.

The most commonly reported adverse reactions in early and late Parkinson's disease in clinical trials were dizziness, involuntary movement, postural hypotension, constipation, hallucinations, headache, difficulty falling asleep, sleepiness, nausea and fatigue. The most commonly reported adverse reactions in clinical trials for Restless Legs Syndrome were nausea, headache, and tiredness.

Pramipexole may cause patients to fall asleep without any warning, even while doing normal daily activities such as driving. When taking pramipexole hallucinations may occur and sometimes patients may feel dizzy, sweaty or nauseated upon standing up. It should be noted that impulse control disorders/compulsive behaviours may occur while taking medicines to treat Parkinson`s disease, including pramipexole.