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tetrabenazine (Rx)Brand and Other Names:Xenazine

 
 
 

Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 12.5mg
  • 25mg
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Huntington Disease

Indicated for treatment of chorea associated with Huntington’s disease

Individualize and slowly titrate dosage over several weeks to identify a dose that reduces chorea and is well tolerated

Total daily dose up to 50 mg/day

  • 12.5 mg PO qDay initially; after 1 week, the dose should be increased to 12.5 mg q12hr
  • Maintenance: Titrate slowly by weekly intervals of 12.5 mg/day to identify dose that reduces chorea and is tolerated
  • If daily dose is 37.5 to 50 mg/day, administer in divided doses q8hr
  • Not to exceed 25 mg per single dose for total daily dosage between 37.5-50 mg/day

Total Daily dose >50 mg/day

  • If >50 mg/day is required, test and genotype to determine if poor or extensive metabolizers of CYP2D6; not to exceed 100 mg/day or 37.5 mg/dose
  • Dose maintenance requirements are dependent on CYP2D6 genotype (see Dosage Modifications)

Dosage Modifications

CYP2D6 extensive/intermediate metabolizers

  • Extensive metabolizers may require dose >50 mg/day
  • If total daily dose >50 mg/day, administer in divided doses q8hr
  • Titrate slowly by 12.5 mg/day qWeek to identify dose that reduces chorea and is tolerated
  • If >50 mg/day is required, do not to exceed 37.5 mg per single dose or a total daily dose of 100 mg/day

CYP2D6 poor metabolizers

  • Not to exceed 25 mg per single dose or a total daily dose of 50 mg/day

Hepatic impairment

  • Contraindicated; it is not possible to adjust the dose to ensure safe use

Dosing Considerations

May take with or without food

Dosage interruption >5 days: Retitrate dose when treatment resumed

Dosage interruption <5 days: May resume at previous maintenance dose without titration

Suspend upward dosage titration and reduce dose; discontinue if adverse reaction (intolerable effects such as: akathisia, restlessness, parkinsonism, insomnia, depression, suicidality, anxiety, sedation) does not resolve (may stop without taper)

Treatment discontinuation

  • May discontinue without tapering
  • Chorea may re-emerge within 12-18 hr after last dose

Tardive Dyskinesia (Off-label)

Investigational (see www.clinicaltrials.gov)

Safety and efficacy not established

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Interactions

Interaction Checker

tetrabenazine and

No Results

     
     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Sedation/somnolence (31%)

            Fatigue (22%)

            Insomnia (22%)

            Depression (19%)

            Akathisia (19%)

            Extrapyramidal event (15%)

            Anxiety (15%)

            Nausea (13%)

            1-10%

            Irritability (9%)

            Bruising (6%)

            Vomiting (6%)

            Decreased appetite (4%)

            Dysuria (4%)

            Obsessive reaction (4%)

            Imbalance (9%)

            Parkinsonism/bradykinesia (9%)

            Dizziness (4%)

            Dysarthria (4%)

            Unsteady gait (4%)

            Headache (4%)

            Frequency Not Defined

            QTc prolongation

            Neuroleptic malignant syndrome

            Orthostatic Hypotension

            Restlessness and agitation

            Dysphagia

            Depression and suicidality

            Postmarketing Reports

            Nervous system disorders: Tremor

            Psychiatric disorders: Confusion, worsening aggression, depression/suicidality

            Respiratory, thoracic and mediastinal disorders: Pneumonia

            Skin and subcutaneous tissue disorders: Hyperhidrosis, skin rash

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            Warnings

            Black Box Warnings

            Increased risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington’s disease

            Balance risks of depression and suicidality with the clinical need for control of choreiform movements when considering the use of tetrabenazine

            Monitor for emergence or worsening of depression, suicidality, or unusual changes in behavior

            Inform patients, caregivers and families of the risk of depression and suicidality and instruct to report behaviors of concern promptly to the treating physician

            Caution in patients with a history of depression or prior suicide attempts or ideation

            Contraindicated in patients who are actively suicidal, and in patients with untreated or inadequately treated depression

            Contraindications

            Hypersensitivity

            Hepatic impairment

            Patients who are actively suicidal, or who have untreated or inadequately treated depression (see Black Box Warnings)

            Concomitant MAO inhibitor or within 14 days of discontinuing MAO inhibitor

            Reserpine

            • Do not use tetrabenazine and reserpine concomitantly
            • Reserpine binds irreversibly to VMAT2 and the duration of its effect is several days
            • Caution when switching from reserpine to tetrabenazine; wait for chorea to re-emerge before administering tetrabenazine to avoid overdosage and major CNS depletion of serotonin and norepinephrine
            • At least 20 days should elapse after stopping reserpine before starting tetrabenazine

            Cautions

            Not indicated for treatment of levodopa-induced dyskinetic movements

            Should only be used by physicians experienced with treatment of hyperkinetic disorders

            May cause depression; discontinue at first sign

            May induce symptoms of Parkinsonism, including symptoms of tardive dyskinesia; akathisia, restlessness, and agitation may occur; reduce dose or discontinue

            Dysphagia, a component of Huntington chorea, may also be caused by dopamine antagonists such as tetrabenazine

            Neuroleptic malignant syndrome (NMS) reported; clinical manifestations include hyperpyrexia, muscle rigidity, altered mental status and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmia); additional signs include elevated creatinine phosphokinase, myoglobinuria, rhabdomyolysis, and acute renal failure

            May cause sedation/somnolence; avoid alcohol and other sedative drugs

            May prolong QTc interval

            May cause orthostatic hypotension

            Concomitant use of neuroleptics (eg, haloperidol, chlorpromazine, risperidone, olanzapine) may cause additive effects of QTc prolongation, NMS, and extrapyramidal disorders

            Caution with poor CYP2D6 metabolizers or drugs that inhibit CYP2D6 (eg, fluoxetine, paroxetine, quinidine); may markedly increase exposure to tetrabenazine active metabolites (alpha- and beta-HTBZ)

            Hyperprolactinemia has resulted from dopaminergic antagonists

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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: Unknown whether distributed in breast milk

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Reversibly inhibits human vesicular monoamine transporter type 2 (VMAT2), resulting in decreased uptake of monoamines (eg, dopamine, serotonin, norepinephrine, histamine) into synaptic vesicles and depletion of monoamine stores from nerve terminals

            This effect is similar to reserpine, but with less peripheral activity and is shorter-acting

            Absorption

            Extent of absorption is at least 75%

            Distribution

            Protein Bound: 82-85%; 59-68% (metabolites)

            Parent drug and metabolites bind to melanin-containing tissues (ie, eye, skin)

            Rapidly distributed in brain (highest binding in striatum, lowest binding in cortex)

            Metabolism

            Rapid and extensively metabolized in liver by carbonyl reductase to active metabolites

            Metabolites (active): alpha-hydroxytetrabenazine, beta-hydroxytetrabenazine

            Active metabolites are predominantly metabolized by CYP2D6

            Elimination

            Half-Life: 7 hr (alpha-hydroxytetrabenazine); 5 hr (beta-hydroxytetrabenazine)

            Excretion: 75% urine; 7-16% feces; excreted mostly as metabolites

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            Formulary

            FormularyPatient Discounts

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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
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            OR Other Restrictions
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