FDA Approves First Drug for
Treatment of Chorea in
Huntington’s Disease
 August 15, 2008
The U.S. Food and Drug Administration has approved Xenazine (tetrabenazine)
for the treatment of chorea in people with Huntington’s disease. Chorea is the
jerky, involuntary movement that occurs in people with this disease.

Xenazine is a new drug and is the first treatment of any kind approved in the
United States for any symptom of Huntington’s disease. Currently there are no
other drugs that are FDA-approved to treat chorea.

Serious side effects reported with use of Xenazine include depression and
suicidal thoughts and actions. Xenazine should not be used in patients who are
actively suicidal or in patients with untreated depression. Concerns about the risk
of suicide are heightened in all patients with Huntington’s disease.

Huntington's disease is a rare, inherited neurological disorder affecting about 1
in 10,000 people in the United States. The disease results from genetically
programmed degeneration of brain cells. The deterioration causes uncontrolled
movements, loss of intellectual faculties, and emotional disturbance. Huntington’s
disease is passed from parent to child through a gene mutation. Each child of a
parent with the disease has a 50 percent chance of inheriting the mutation.

About 30,000 people in the United States have Huntington’s disease and
another 200,000 are at risk of developing the condition. Symptoms commonly
develop between ages 30 and 50. The disease progresses slowly and a person
may live for another 15-20 years after the onset of symptoms.

Xenazine decreases the amount of dopamine available to work at relevant
synapses in the brain. Dopamine is a chemical that communicates between
certain nerve cells in the brain. In patients with Huntington’s disease, this system
is overactive and results in the abnormal movements called chorea. Xenazine
decreases the amount of dopamine available to interact with certain nerve cells,
thereby decreasing the involuntary movements.

The effectiveness and safety of Xenazine was established primarily in a
randomized, double-blind, placebo-controlled multi-center clinical trial. Patients
treated with Xenazine had a significant improvement in chorea compared to
patients treated with placebo. Other studies provided additional support for this
effect.

The most common side effects reported by patients using Xenazine in clinical
trials include insomnia, depression, drowsiness, restlessness and nausea.

While 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. Health care professionals and family members of patients taking
the drug should pay attention to all of the facets of the disease.

Xenazine has been approved with a required Risk Evaluation and Mitigation
Strategy (REMS) to ensure that the benefits of the drug outweigh its risks,
particularly the risks of depression and suicidal thoughts and actions. REMS is a
strategy to manage a known or potential serious risk associated with a drug or
biological product.

The REMS includes educational materials for prescribers, pharmacists and
patients (and their caregivers) to help minimize adverse effects associated with
Xenazine. 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. The FDA requires that the Medication Guide be handed out
with every prescription for the drug dispensed.

Xenazine was granted orphan drug designation by the FDA. A drug is eligible for
orphan drug designation if it is intended to treat a disease or condition that
affects less than 200,000 people in the United States. A drug is also eligible for
orphan drug designation if it is intended to treat a disease or condition that
affects more than 200,000 people in the United States, but there is no
reasonable expectation that the cost of developing and making available a drug
for the disease or condition will be recovered from sales of the drug.

Xenazine is manufactured by Prestwick Pharmaceuticals, Inc., Washington, D.C.

SOURCE FDA Approves First Drug for Treatment of Chorea in
Huntington’s Disease FDA News August 15, 2008
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