First data showing outcomes of two double-blind studies investigating the efficacy, safety and tolerability of Mirapexin/Sifrol (pramipexole) in a prolonged release, once daily formulation, for the treatment of Parkinson's disease (PD), were presented at the American Academy of Neurology Annual Meeting (AAN) in Seattle, USA.

The first study compared the efficacy, safety and tolerability of pramipexole prolonged release versus pramipexole immediate release and placebo, in patients with early PD treated for up to 33 weeks. A confirmatory statistical analysis conducted at week 18 demonstrated that the pramipexole prolonged release formulation was superior to placebo and had a comparable efficacy to the pramipexole immediate release formulation, at the same daily dosage. A descriptive statistical analysis showed maintenance of efficacy after 33 weeks of treatment compared to 18 weeks of treatment in both pramipexole groups, while placebo patients worsened from week 18 to week 33.

Commenting on the study, Werner Poewe, professor of Neurology and director of the Department of Neurology, University Hospital Innsbruck, Austria said, "Every patient with Parkinson's disease will have a different range of symptoms or requirements. Bearing this in mind, it is important to provide patients with a treatment regimen that not only suits their individual needs, but also gives reassurance to physicians that new formulations are as good as their current formulations when it comes to efficacy, safety and tolerability."

The second study, also conducted in patients with early PD, assessed the efficacy and safety of an overnight switch from pramipexole immediate release to a pramipexole prolonged release formulation, at the same daily dose. The study showed that 84.5 per cent of patients were switched successfully from pramipexole immediate release to pramipexole prolonged release (a successful switch was defined as no worsening by more than 15 per cent from baseline in the Unified Parkinson's Disease Rating Scale (UPDRS) II+III score and no drug-related adverse events leading to discontinuation).

Results from trials in patients with advanced PD will be presented later this year and are expected to further support a Mirapexin/Sifrol (pramipexole) once daily, prolonged release formulation. The new formulation for pramipexole is currently under evaluation by the US and European regulatory agencies.

Pramipexole (known under the trade names Mirapexin, Sifrol, Mirapex and Pexola) 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 2006 for the symptomatic treatment of moderate to severe idiopathic Restless Legs Syndrome (RLS).