First drug to treat Huntington’s disease approved by FDA
By Graciela Gutierrez
In the United States there are about 30,000 people suffering from Huntington's disease, a rare, inherited neurological disorder. Another 200,000 are at risk of developing the debilitating disease. Now, for the first time, an effective treatment for symptoms has been approved by the U.S. Food and Drug Administration after study results by the Huntington Study Group and Baylor College of Medicine in Houston showed the drug's effectiveness.
How tetrabenazine works
The abnormal involuntary movements, known as chorea, associated with Huntington's disease are eased by using a drug called Tetrabenazine, which will be marketed as Xenazine®.
“Chorea is thought to be caused by over activity of the neurotransmitter dopamine. Tetrabenazine works by depleting dopamine levels in the brain,” said Joseph Jankovic, M.D., professor of neurology and director of the Parkinson Disease Center and Movement Disorder Clinic at BCM.
Years of research lead to approval
"In 1979, I was granted special permission from the FDA to treat patients with the drug,” said Jankovic, also distinguished chair in movement disorders at BCM. “Since that time I’ve treated thousands of people with tetrabenazine and have seen amazing results that translated into marked improvement in the quality of life”.
When the FDA began the approval process for tetrabenazine, Jankovic and his colleagues presented experience with the drug accumulated over more than a quarter of century. In addition Jankovic and his BCM colleagues participated in a double-blind, a placebo-controlled multi-center clinical trial conducted by the Huntington Study Group involving more than 80 participants to establish effectiveness and safety.
Results
Those treated with tetrabenazine had a significant improvement in chorea compared to patients treated with a placebo. Despite some side effects, such as mood changes, slowness of movement, insomnia, restlessness and nausea, the FDA panel unanimously recommended approval of the drug.
"Other drugs used in the past to treat Huntington’s disease resulted in permanent side effects, including tardive dyskinesia which is a drug induced movement disorder,” Jankovic said. “This side effect has not occurred with tetrabenazine and most other side effects can be lessened with smaller dosages without lasting effect.”
Xenazine, developed in the United States by Prestwick Pharmaceuticals, Inc, has been approved with a required Risk Evaluation and Mitigation Strategy to ensure the benefits of the drug outweigh its risks.
