Tetrabenazine
Generic Name: tetrabenazine
Brand Names:
Tetrabenazine
11 DESCRIPTION Tetrabenazine is a monoamine depletor for oral administration. The molecular weight of tetrabenazine is 317.43 g/mol; the pKa is 6.51. Tetrabenazine is a hexahydro-dimethoxy-benzoquinolizine derivative and has the following chemical name: cis rac –1,3,4,6,7,11b-hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H-benzo[a]quinolizin-2-one.
Overview
11 DESCRIPTION Tetrabenazine is a monoamine depletor for oral administration. The molecular weight of tetrabenazine is 317.43 g/mol; the pKa is 6.51. Tetrabenazine is a hexahydro-dimethoxy-benzoquinolizine derivative and has the following chemical name: cis rac –1,3,4,6,7,11b-hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H-benzo[a]quinolizin-2-one.
Uses
1 INDICATIONS AND USAGE Tetrabenazine tablets are indicated for the treatment of chorea associated with Huntington's disease. Tetrabenazine tablets are a vesicular monoamine transporter 2 (VMAT) inhibitor indicated for the treatment of chorea associated with Huntington's disease ( 1 )
Dosage
2 DOSAGE AND ADMINISTRATION Individualization of dose with careful weekly titration is required. The 1 st week's starting dose is 12.5 mg daily; 2 nd week, 25 mg (12.5 mg twice daily); then slowly titrate at weekly intervals by 12.5 mg to a tolerated dose that reduces chorea. ( 2.1 , 2.2 ) Doses of 37.5 mg and up to 50 mg per day should be administered in three divided doses per day with a maximum recommended single dose not to exceed 25 mg. ( 2.2 ) Patients requiring doses above 50 mg per day should be genotyped for the drug metabolizing enzyme CYP2D6 to determine if the patient is a poor metabolizer (PM) or an extensive metabolizer (EM). ( 2.2 , 5.3 ) Maximum daily dose in PMs: 50 mg with a maximum single dose of 25 mg.
Side Effects
6 ADVERSE REACTIONS The following serious adverse reactions are described below and elsewhere in the labeling: Depression and Suicidality [see Warnings and Precautions ( 5.1 )] Neuroleptic Malignant Syndrome (NMS) [see Warnings and Precautions ( 5.4 )] Akathisia, Restlessness, and Agitation [see Warnings and Precautions ( 5.5 )] Parkinsonism [see Warnings and Precautions ( 5.6 )] Sedation and Somnolence [see Warnings and Precautions ( 5.7 )] QTc Prolongation [see Warnings and Precautions ( 5.8 )] Hypotension and Orthostatic Hypotension [see Warnings and Precautions ( 5.9 )] Hyperprolactinemia [see Warnings and Precautions ( 5.10 )] Binding to Melanin-Containing Tissues [see Warnings and Precautions ( 5.11 )] Most common adverse reactions (>10% and at least 5% greater than placebo) were: Se...
Interactions
7 DRUG INTERACTIONS 7.1 Strong CYP2D6 Inhibitors In vitro studies indicate that α-HTBZ and β-HTBZ are substrates for CYP2D6. Strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, quinidine) markedly increase exposure to these metabolites. A reduction in tetrabenazine dose may be necessary when adding a strong CYP2D6 inhibitor (e.g., fluoxetine, paroxetine, quinidine) in patients maintained on a stable dose of tetrabenazine. The daily dose of tetrabenazine should not exceed 50 mg per day and the maximum single dose of tetrabenazine should not exceed 25 mg in patients taking strong CYP2D6 inhibitors [see Dosage and Administration ( 2.3 ), Warnings and Precautions ( 5.3 ), Use in Specific Populations ( 8.7 ), Clinical Pharmacology ( 12.3 )] .
Warnings
WARNING: DEPRESSION AND SUICIDALITY Tetrabenazine can increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington’s disease. Anyone considering the use of tetrabenazine must balance the risks of depression and suicidality with the clinical need for control of chorea. Close observation of patients for the emergence or worsening of depression, suicidality, or unusual changes in behavior should accompany therapy. 5 WARNINGS AND PRECAUTIONS Periodically reevaluate the benefit and potential for adverse effects such as worsening mood, cognition, rigidity, and functional capacity. ( 5.2 ) Do not exceed 50 mg/day and the maximum single dose should not exceed 25 mg if administered in conjunction with a strong CYP2D6 inhibitor (e.g., fluoxetine, paroxetine). ( 5.3 , 7.1 ) Neuroleptic Malignant Syndrome (NMS): Discontinue if this occurs. ( 5.4 , 7.6 ) Restlessness, agitation, akathisia and parkinsonism: Reduce dose or discontinue if occurs. ( 5.5 , 5.6 ) Sedation/Somnolence: May impair patient’s ability to drive or operate complex machinery. ( 5.7 ) QTc prolongation: Not recommended in combination with other drugs that prolong QTc. 4 CONTRAINDICATIONS Tetrabenazine tablets are contraindicated in patients: Who are actively suicidal, or in patients with untreated or inadequately treated depression [see Warnings and Precautions ( 5.1 )] . With hepatic impairment [see Use in Specific Populations ( 8.6 ), Clinical Pharmacology ( 12.3 )] . Taking monoamine oxidase inhibitors (MAOIs).
Pregnancy
8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of tetrabenazine in pregnant women. Administration of tetrabenazine to rats throughout pregnancy and lactation resulted in an increase in stillbirths and postnatal offspring mortality. Administration of a major human metabolite of tetrabenazine to rats during pregnancy or during pregnancy and lactation produced adverse effects on the developing fetus and offspring (increased mortality, decreased growth, and neurobehavioral and reproductive impairment).
Storage
16.2 Storage Store at 20ºC to 25ºC (68ºF to 77ºF); excursions permitted from 15ºC to 30ºC (59ºF to 86ºF) [see USP Controlled Room Temperature].
Frequently Asked Questions
What is Tetrabenazine used for?▼
1 INDICATIONS AND USAGE Tetrabenazine tablets are indicated for the treatment of chorea associated with Huntington's disease. Tetrabenazine tablets are a vesicular monoamine transporter 2 (VMAT) inhibitor indicated for the treatment of chorea associated with Huntington's disease ( 1 )
What are the side effects of Tetrabenazine?▼
6 ADVERSE REACTIONS The following serious adverse reactions are described below and elsewhere in the labeling: Depression and Suicidality [see Warnings and Precautions ( 5.1 )] Neuroleptic Malignant Syndrome (NMS) [see Warnings and Precautions ( 5.4 )] Akathisia, Restlessness, and Agitation [see Warnings and Precautions ( 5.5 )] Parkinsonism [see Warnings and Precautions ( 5.6 )] Sedation and Somnolence [see Warnings and Precautions ( 5.7 )] QTc Prolongation [see Warnings and Precautions ( 5.8 )] Hypotension and Orthostatic Hypotension [see Warnings and Precautions ( 5.9 )] Hyperprolactinemia [see Warnings and Precautions ( 5.10 )] Binding to Melanin-Containing Tissues [see Warnings and Precautions ( 5.11 )] Most common adverse reactions (>10% and at least 5% greater than placebo) were: Se...
Can I take Tetrabenazine during pregnancy?▼
8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of tetrabenazine in pregnant women. Administration of tetrabenazine to rats throughout pregnancy and lactation resulted in an increase in stillbirths and postnatal offspring mortality. Administration of a major human metabolite of tetrabenazine to rats during pregnancy or during pregnancy and lactation produced adverse effects on the developing fetus and offspring (increased mortality, decreased growth, and neurobehavioral and reproductive impairment).
What are the important warnings for Tetrabenazine?▼
WARNING: DEPRESSION AND SUICIDALITY Tetrabenazine can increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington’s disease. Anyone considering the use of tetrabenazine must balance the risks of depression and suicidality with the clinical need for control of chorea. Close observation of patients for the emergence or worsening of depression, suicidality, or unusual changes in behavior should accompany therapy. 5 WARNINGS AND PRECAUTIONS Periodically reevaluate the benefit and potential for adverse effects such as worsening mood, cognition, rigidity, and functional capacity. ( 5.2 ) Do not exceed 50 mg/day and the maximum single dose should not exceed 25 mg if administered in conjunction with a strong CYP2D6 inhibitor (e.g., fluoxetine, paroxetine). ( 5.3 , 7.1 ) Neuroleptic Malignant Syndrome (NMS): Discontinue if this occurs. ( 5.4 , 7.6 ) Restlessness, agitation, akathisia and parkinsonism: Reduce dose or discontinue if occurs. ( 5.5 , 5.6 ) Sedation/Somnolence: May impair patient’s ability to drive or operate complex machinery. ( 5.7 ) QTc prolongation: Not recommended in combination with other drugs that prolong QTc. 4 CONTRAINDICATIONS Tetrabenazine tablets are contraindicated in patients: Who are actively suicidal, or in patients with untreated or inadequately treated depression [see Warnings and Precautions ( 5.1 )] . With hepatic impairment [see Use in Specific Populations ( 8.6 ), Clinical Pharmacology ( 12.3 )] . Taking monoamine oxidase inhibitors (MAOIs).
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Medical Disclaimer
This drug information is for educational purposes only and should not replace professional medical advice. Drug information is sourced from the FDA National Drug Code Directory and Structured Product Labeling. Always consult with a healthcare provider before starting, stopping, or changing any medication.