Clinical Trial Results Suggest Long-Term Treatment Benefit of Tetrabenazine for Chorea Associated with Huntington’s Disease

Findings Presented at 59th Annual Meeting of the American Academy of Neurology

Boston, Massachusetts – May 3, 2007 – New data show the investigational drug tetrabenazine maintained reduction of chorea associated with Huntington’s disease (HD) up to 80 weeks in those patients who successfully completed treatment in a 13-week trial. These data suggest that tetrabenazine can be used successfully to sustain reduced chorea burden in long-term use.

“These findings demonstrate the potential benefit of tetrabenazine as maintenance therapy for U.S. patients who present with troublesome chorea,” said Dr. Samuel Frank, Assistant Professor of Neurology at Boston University Medical Center, who presented the data on behalf of the Huntington Study Group. “Following individualized patient dosing based upon response and side effects, we were able to maintain reduced chorea burden.”

Tetrabenazine is designed to reversibly stop the release of dopamine, a brain chemical involved in abnormal movements such as chorea. Chorea can be a debilitating feature of a number of neurological diseases, characterized by excessive, involuntary and repetitive movements that may flow from one body part to another. The movements may involve the face, limbs or the entire body. HD is one of the more notable diseases with chorea that may at first be limited to the fingers and toes. However, as the disease advances, the abnormal movements become more widespread.

Study Design and Results
This study was an open-label study for patients who successfully completed treatment in a 13-week double-blind, placebo-controlled Phase III trial. In all, 75 eligible patients enrolled in the 80-week study and were given tetrabenazine in tablet form, which was gradually increased in dose to the best individualized maintenance dose based on each research participant’s response and side effects.

Forty-five of the original 75 patients completed 80 weeks of the open-label study. At week 80, disease symptoms as measured by the Total Maximal Chorea Score were statistically significantly reduced, as compared to baseline in the open-label study, within subjects with significant benefits seen throughout the study’s duration. The most commonly observed adverse events were sleepiness, depressed mood, anxiety, chorea, insomnia, and an inner feeling of restlessness (akathisia). Serious adverse events judged by study investigators to be possibly or probably related to tetrabenazine use included: fall (two patients), pneumonia (two patients), increased depression, akathisia, agitation and trouble swallowing (dysphagia). Nine patients withdrew from the study due to adverse events.

About Huntington’s Disease
Huntington’s disease (HD) is an inherited degenerative brain disorder that affects 1 in 10,000 Americans and causes involuntary movements (chorea) and deterioration in the ability to think, walk, talk and reason. HD is hereditary, with each child of an affected parent having a 50% chance of inheriting the gene that causes HD. The disease does not skip generations, and everyone who carries the gene will develop the disease. Most people with HD develop the illness between the ages of 30 and 45. At this time, there is no way to stop, slow or reverse the course of HD, and current treatments are aimed at alleviating the troublesome symptoms of the disease.

About the Huntington Study Group
This clinical study was organized and conducted by the Huntington Study Group, a non-profit, cooperative group of Huntington’s disease experts from medical centers in North America, Europe and Australia who are dedicated to improving treatment for persons affected by Huntington’s disease. For more information, visit their web sites at www.Huntington-Study-Group.org and www.HuntingtonProject.org.

About Tetrabenazine
Tetrabenazine has been licensed to Prestwick Pharmaceuticals, Inc. for marketing in the United States and Canada by Cambridge Laboratories (Ireland) Limited, which has worldwide rights to the product. Cambridge markets tetrabenazine in the UK under the brand name XENAZINE®.

Tetrabenazine is available in some European markets and New Zealand under the brand name XENAZINE and in Canada and other European markets as NITOMAN® for the treatment of hyperkinetic movement disorders. Prestwick Pharmaceuticals, Inc. has filed a New Drug Application with the FDA to market the product under the trade name XENAZINE, and review of the application is pending.

About Prestwick Pharmaceuticals
Prestwick is a late-stage product-based biopharmaceutical company engaged in the development and marketing of drugs for diseases of the CNS. The portfolio of drugs addresses significant unmet medical needs in such CNS disorders as Huntington’s disease, Parkinson’s disease, and schizophrenia.