Xenazine Side Effects

Generic Name: tetrabenazine

Please note - some side effects for Xenazine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Xenazine - for the Consumer

Xenazine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Xenazine:

Decreased appetite; dizziness; drowsiness; nausea; tiredness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); fainting; fast or irregular heartbeat; fever; increased sweating; increased or unusual coughing; new or worsening muscle problems (eg, body stiffness, tremor or shaking, trouble moving or keeping your balance, unsteadiness); new or unusual involuntary muscle movements of the face, mouth, jaws, or tongue (eg, fast eye blinking, lip smacking, mouth puckering or chewing movements, puffing of cheeks, sticking out of the tongue); new or worsening mental or mood problems (eg, agitation or aggressiveness, anxiety, confusion, depression or sadness, panic attack, restlessness, or unusual behavior changes); persistent trouble sleeping; severe nausea or vomiting; severe or persistent dizziness; shortness of breath; suicidal thoughts or actions; trouble speaking or swallowing; trouble urinating; unusual bruising or bleeding; vision changes.

Xenazine Side Effects - for the Professional

Xenazine

During its development, tetrabenazine was administered to 773 unique subjects and patients. The conditions and duration of exposure to tetrabenazine varied greatly, and included single and multiple dose clinical pharmacology studies in healthy volunteers (n=259) and open-label (n=529) and double-blind studies (n=84) in patients.

The prescriber should be aware that the figures in the tables and tabulations cannot be used to predict the incidence of adverse effects in the course of usual medical practice where patient characteristics and other factors differ from those that prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different treatments, uses, and investigators. The cited figures, however, do provide the prescribing physician with some basis for estimating the relative contribution of drug and non-drug factors to the adverse event incidence rate in the population studied.

In a randomized, 12-week, placebo-controlled clinical trial of HD subjects, adverse events (AEs) were more common in the tetrabenazine group than in the placebo group.  Forty-nine of 54 (91%) patients who received Xenazine experienced one or more AEs at any time during the study. The AEs most commonly reported (over 10%, and at least 5% greater than placebo) were sedation/somnolence (31% vs. 3% on placebo), fatigue (22% vs. 13% on placebo), insomnia (22% vs. 0% on placebo), depression (19% vs. 0% on placebo), akathisia (19% vs. 0% on placebo), and nausea (13% vs. 7% on placebo). The number and percentage of the most commonly reported AEs that occurred at any time during the study in ≥4% of tetrabenazine-treated patients, and with a greater frequency than in placebo-treated patients, are presented in Table 1 in decreasing order of frequency within body systems for the tetrabenazine group.

Dose titration was discontinued or dosage of study drug was reduced because of one or more AEs in 28 of 54 (52%) patients randomized to tetrabenazine. These AEs consisted of sedation (15), akathisia (7), parkinsonism (4), depression (3), anxiety (2), fatigue (1) and diarrhea (1). Some patients had more than one AE and are therefore counted more than once.

The following table describes the incidence of events considered to be extrapyramidal adverse reactions.

Laboratory Tests

No clinically significant changes in laboratory parameters were reported in clinical trials with Xenazine. In controlled clinical trials, Xenazine caused a small mean increase in ALT and AST laboratory values as compared to placebo.

Vital Signs

In controlled clinical trials, tetrabenazine did not affect blood pressure, pulse, and body weight. Orthostatic blood pressure was not consistently measured in the Xenazine clinical trials.

DRUG ABUSE AND DEPENDENCE

Controlled Substance Class

Tetrabenazine is not a controlled substance.

Physical and Psychological Dependence

Clinical trials did not reveal any tendency for drug seeking behavior, though these observations were not systematic. Abuse has not been reported from the postmarketing experience in countries where tetrabenazine has been marketed. Abrupt discontinuation of tetrabenazine from patients did not produce symptoms of withdrawal or a discontinuation syndrome; only symptoms of the original disease were observed to re-emerge. As with any CNS-active drug, physicians should carefully evaluate patients for a history of drug abuse and follow such patients closely, observing them for signs of tetrabenazine misuse or abuse (such as development of tolerance, incrementation of dose, drug-seeking behavior).

Side Effects by Body System

Psychiatric

Psychiatric side effects have included sedation, somnolence, insomnia, depression, anxiety, irritability, and obsessive reaction.

Nervous system

Nervous system side effects have included akathisia, balance difficulty, Parkinsonism, bradykinesia, dizziness, dysarthria, and unsteady gait.

Other

Other side effects have included fatigue, falls, and ecchymosis.

Gastrointestinal

Gastrointestinal side effects have included nausea and vomiting.

Cardiovascular

Cardiovascular side effects have included hypotension.

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