Merck Serono and Italian partner Newron Pharmaceuticals say they have started new late-stage studies of their investigational Parkinson's disease drug safinamide, this time at a lower dose.

This follows rather disappointing preliminary data presented in August of a 12-month extension study of a six-month Phase III trial of safinamide as an add-on treatment to dopamine agonist therapy in patients with early stage Parkinson's disease. This revealed that the drug failed to reach statistical significance when data from both safinamide dose groups (50-100 mg and 150-200 mg) were pooled.

The new Phase III trial, called MOTION, will now evaluate the safety and efficacy of safinamide at 50mg and 100mg once-daily doses combined with standard therapy. The move to go for the lower dose is the result of a clinical development plan previously discussed with regulatory authorities, the firms said.

The MOTION study is a six-month trial that will involve more than 650 patients with early idiopathic Parkinson’s disease and its primary endpoint will be to demonstrate that safinamide, an alpha-aminoamide derivative, helps improve control motor functions. Its secondary goals include an improvement in cognitive functions and quality of life.

Merck Serono obtained exclusive worldwide rights from Newron to develop, manufacture and commercialise safinamide in Parkinson’s disease, Alzheimer’s and other therapeutic applications in October 2006.