ROCKVILLE, Md., Aug. 15 — The FDA has approved tetrabenazine (Xenazine), the first agent for chorea in Huntington’s disease, the involuntary jerky movements that are a hallmark of the condition.
“For the first time, there is a treatment that can help patients with this disease gain some quality of life,” said Timothy Cot?©, M.D., M.P.H., director of FDA’s Office of Orphan Products Development.
Tetrabenazine decreases the amount of dopamine available to work at relevant synapses in the brain, which decreases involuntary movements.
The effectiveness and safety of tertrabenazine was established in a randomized, double-blind, placebo-controlled multicenter clinical trial. Patients treated with tetrabenazine had a significant improvement in chorea compared with patients treated with placebo. Other studies provided additional support for this effect.
The most common side effects of tetrabenazine in clinical trials included insomnia, depression, drowsiness, restlessness and nausea.
Although the drug has been shown to decrease chorea in the short-term, it also showed slight worsening in mood, cognition, rigidity, and functional capacity in clinical trials.
As a result, tetrabenazine has been approved with a required Risk Evaluation and Mitigation Strategy (REMS) to ensure that its benefits outweigh its risks, particularly the risks of depression and suicidal thoughts and actions.
The tetrabenazine REMS includes educational materials for prescribers, pharmacists, and patients (and their caregivers) to help minimize adverse effects associated with tetrabenazine treatment. It also includes a medication guide, which informs patients and their caregivers about the risks of depression, suicidal thoughts and actions, and other side effects.
Tetrabenazine, which is manufactured by Prestwick Pharmaceuticals, Inc., of Washington, was granted orphan drug designation by the FDA.