Nitoman (Tetrabenazine)

Tetrabenazine is indicated for movement‑disorder conditions that involve excessive dopaminergic activity, where reduction of involuntary movements is clinically required.

• Huntington's disease: reduces chorea, improves motor coordination, may enhance daily functioning, and can decrease caregiver burden in patients with manifest disease.
• Tardive dyskinesia: lessens involuntary facial, tongue, and limb movements that arise from chronic antipsychotic exposure, improves quality of life, and supports better adherence to psychiatric therapy.
• Other choreiform disorders: may be used under specialist supervision to control involuntary movements in conditions such as Wilson disease or neuroacanthocytosis.

• Tetrabenazine acts by reversibly inhibiting the vesicular monoamine transporter 2 (VMAT2) located on presynaptic neuronal vesicles. This blockade prevents the uptake of dopamine, serotonin, norepinephrine and other monoamines into storage vesicles, leading to depletion of these neurotransmitters in the synaptic cleft. The resulting reduction in dopaminergic signaling diminishes the hyperkinetic movements characteristic of Huntington’s disease and tardive dyskinesia.

Tetrabenazine may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Drowsiness: feeling of increased sleepiness or fatigue.
• Nausea: mild to moderate stomach upset.
• Depression: low mood that may require monitoring.
• Weight loss: reduced appetite leading to decreased body weight.
• Insomnia: difficulty falling or staying asleep.
• Dry mouth: reduced salivation.
• Dizziness: sensation of lightheadedness or unsteadiness.

Serious or Rare Side Effects

• Suicidal ideation: thoughts of self‑harm requiring immediate medical attention.
• Severe depression: marked depressive episodes that may be life‑threatening.
• QT prolongation: cardiac rhythm disturbance that can lead to arrhythmia.
• Neuroleptic malignant‑like syndrome: rare hyperthermia and muscle rigidity.

When prescribing Nitoman, clinicians should observe several safety measures.

• Monitor depression: assess patients regularly for mood changes and suicidal thoughts.
• Avoid in severe hepatic impairment: dose adjustment or contraindication may be required.
• Use caution with other CNS depressants: increased sedation risk.
• Adjust dose in renal impairment: consider reduced dosing in moderate renal dysfunction.
• Pregnancy and lactation: safety not established; avoid use unless benefit outweighs risk.
• Store at below 25°C: keep in the original container, protect from moisture and light.

Tetrabenazine interacts with several drug classes; awareness helps prevent adverse events.

Major Interactions (Avoid)

• MAO inhibitors: risk of hypertensive crisis and severe serotonin syndrome.
• QT‑prolonging agents: additive effect on cardiac repolarization increasing arrhythmia risk.
• CNS depressants (e.g., opioids, benzodiazepines): may cause excessive sedation or respiratory depression.

Moderate Interactions (Monitor Closely)

• Antidepressants (SSRIs, SNRIs): may enhance serotonergic effects.
• Antihypertensives: tetrabenazine can potentiate blood pressure lowering.
• Anticholinergic drugs: may increase anticholinergic burden and cognitive effects.