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Huntington's Chorea

The hallmark presentation of Huntington's disease includes motor, cognitive, and psychiatric symptoms.¹ Chorea is the most visible of the motor symptoms, affecting about 90% of the patient population.² The signs of chorea can be recognized in all stages of Huntington's disease (HD).²

In the various stages of Huntington's disease, chorea may often be a major source of disability.^1,3 Excessive chorea is one of the major factors that may contribute to falls in patients suffering from early to mid-stage HD.⁴

When determining levels of disability, impact of specific tests should be analyzed as well as overall functional status.⁵

A recent Huntington's Study Group (HSG) study of 347 participants (Total Functional Capacity >6) reported that increasing severity of chorea significantly impacted a patient's ability to work, drive, or care for children independently.⁵

The HSG used the total maximal chorea as a predictor of disability which was measured by specific items on the Unified Huntington's Disease Rating Scale (UHDRS) functional checklist.⁵

Self Care
Feeding
Household Chores
Financial Independence
Dressing
Employment

Advanced motor impairment may lead to institutionalization:³

In a study of 3,070 HD patients, including 228 residents in a skilled nursing facility, it was revealed that the major predictor of nursing home placement for patients with HD is advanced motor impairment.³
It was reported that institutionalized patients in the study had a higher frequency of marked chorea (17.7%), bradykinesia (58%), retropulsion (62%), and gait (61%) and balance (93%) dysfunction than those residing at home.³

Xenazine does not cure the cause of HD chorea and does not treat the other symptoms of HD.

Sources:

Rosenblatt A, Ranen NG, Nance MA, Paulsen JS. A Physician's Guide to the Management of Huntington's Disease. 2nd ed. New York, NY: Huntington's Disease Society of America; 1999.
Haddad MS, Cummings JL. Huntington's disease. Neuropsychiatry of the basal ganglia. Psychiatry Clinics of North America 1997;20:791-807
Wheelock VL, Tempkin T, Marder K, et al; and the Huntington Study Group. Predictors of nursing home placement in Huntington disease. Neurology. 2003; 60(6):998-1001.
Grimbergen YAM, Knol MJ, Bloem BR, Kremer BPH, Roos RAC, Munneke M. Falls and gait disturbances in Huntington's disease. Mov Dis. 2008;23(7):970-976.
Frank SA, Marshall F, Plumb S, Oakes D, Shoulson I, Kieburtz K; and the CARE-HD Investigators of the Huntington Study Group. Functional decline due to chorea in Huntington's disease: P03.034. Neurology. 2004;62(7)(suppl S5):A204.

XENAZINE® (tetrabenazine) Tablets

Indications and Usage:

Xenazine is indicated for the treatment of chorea associated with Huntington’s disease.

Important Safety Information:

DEPRESSION AND SUICIDALITY

XENAZINE can increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington’s disease. Anyone considering the use of XENAZINE must balance the risks of depression and suicidality with the clinical need for control of choreiform movements. Close observation of patients for the emergence or worsening of depression, suicidality, or unusual changes in behavior should accompany therapy. Patients, their caregivers, and families should be informed of the risk of depression and suicidality and should be instructed to report behaviors of concern promptly to the treating physician.

Particular caution should be exercised in treating patients with a history of depression or prior suicide attempts or ideation, which are increased in frequency in Huntington’s disease. XENAZINE is contraindicated in patients who are actively suicidal, and in patients with untreated or inadequately treated depression.

Xenazine is also contraindicated in patients who have impaired hepatic function or are taking monoamine oxidase inhibitors or reserpine. At least 20 days should elapse after stopping reserpine before starting Xenazine.

The need for therapy should be evaluated on an ongoing basis with the patient’s doctor. Xenazine should be titrated slowly over several weeks for a dose that is appropriate for each patient. Before a dose greater than 50 mg is administered, the patient’s CYP2D6 metabolizer status should be determined.

Neuroleptic malignant syndrome (NMS), akathisia, agitation, parkinsonism, dysphagia, and QT prolongation–related arrhythmias have been reported with use of Xenazine. Xenazine should not be used in combination with drugs known to prolong QTc (which in certain circumstances can lead to torsades de pointes and/or sudden death), in patients with congenital long QT syndrome, or in patients with a history of cardiac arrhythmias. A potentially irreversible syndrome of involuntary, dyskinetic movements called tardive dyskinesia (TD) may develop in patients treated with neuroleptic drugs. If signs and symptoms of TD appear in a patient treated with Xenazine, drug discontinuation should be considered. Adverse reactions associated with Xenazine, such as QTc prolongation, NMS, and extrapyramidal disorders, may be exaggerated by concomitant use of dopamine antagonists.

Xenazine elevates serum prolactin concentrations. Xenazine may induce sedation and somnolence (sleepiness or drowsiness) and may impair the ability to drive or operate dangerous machinery.

Some adverse events such as depression, fatigue, insomnia, sedation/somnolence, parkinsonism, and akathisia may be dose-dependent. If the adverse effect does not resolve or decrease, consideration should be given to lowering or discontinuing Xenazine. The most commonly reported adverse events with Xenazine compared to placebo were sedation/somnolence (31% vs 3%), fatigue (22% vs 13%), insomnia (22% vs 0%), depression (19% vs 0%), akathisia (19% vs 0%), anxiety (15% vs 3%), and nausea (13% vs 7%).

For more information, please see Full Prescribing Information, including Boxed Warning.

®Xenazine is a registered trademark of Biovail Laboratories International (Barbados) S.R.L.

XZN118

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