Tetrabez

Indications

Tetrabenazine is used to reduce chorea (sudden, jerky, uncontrolled movements) in Huntington's disease. Specialists may also use it for some other movement disorders, such as tardive dyskinesia, tics and hemiballismus. It is started and adjusted by a neurologist or psychiatrist.

How It Works

Tetrabenazine blocks a transporter called VMAT2 that packs chemical messengers, mainly dopamine, into nerve endings. With less dopamine released, the brain sends fewer signals for unwanted movements.

Dosage and Administration

As prescribed. Treatment starts at a low dose (often 12.5 mg once a day) and is increased slowly, usually weekly, until movements are controlled or side effects appear. Higher daily doses are split into two or three doses. Take it by mouth with or without food. Do not stop it suddenly or change the dose without the doctor's advice.

Interactions

• Do not take with MAO inhibitor antidepressants (such as Selegiline in high doses or Phenelzine) or within 14 days of stopping them, or with Reserpine.
• Fluoxetine, Paroxetine, Bupropion and Quinidine raise tetrabenazine levels; the dose must be limited.
• Medicines that affect heart rhythm (such as some antipsychotics, Amiodarone, some antibiotics like Moxifloxacin) add to the risk of rhythm problems.
• Antipsychotic medicines such as Haloperidol increase the risk of stiffness and restlessness.
• Alcohol, sleeping pills and other sedating medicines increase drowsiness.

Contraindications

• Depression that is untreated or not well controlled, or current thoughts of suicide.
• Liver impairment.
• Taking MAO inhibitors or Reserpine, or Deutetrabenazine or Valbenazine.
• Allergy to tetrabenazine or any ingredient of the product.

Side Effects

Common: drowsiness, tiredness, low mood, restlessness or inability to keep still (akathisia), anxiety, difficulty sleeping, nausea, and stiffness or slow movement like Parkinson's disease.

Get urgent medical help if you have: worsening depression or any thoughts of suicide or self-harm (family members should also watch for mood changes); high fever with stiff muscles, confusion and sweating (a rare reaction called neuroleptic malignant syndrome); fainting, a fast or irregular heartbeat; or trouble swallowing.

Pregnancy and Lactation

There is little information on safety in pregnancy and breastfeeding. Use only if the doctor decides the benefit is greater than the risk. Tell the doctor if you are pregnant, planning pregnancy or breastfeeding.

Precautions and Warnings

• Patients and families should watch closely for changes in mood or behaviour, especially when starting or increasing the dose.
• It can cause drowsiness; do not drive or use machines until you know how it affects you.
• Tell the doctor about heart rhythm problems, low potassium or magnesium, or a history of depression.
• Stand up slowly, as it may cause dizziness on standing.

Overdose

Too much may cause severe drowsiness, sweating, low blood pressure, confusion, vomiting, shaking and abnormal movements. Seek emergency medical help.

Therapeutic Class

VMAT2 inhibitor; medicine for movement disorders (chorea).

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.