Tetrabenazin

Tetrabenazin, also known as tetrabenazine in English, is a prescription medicine that acts as a reversible inhibitor of vesicular monoamine transporter 2 (VMAT2). By blocking VMAT2, it reduces the storage and release of monoamines—principally dopamine—in presynaptic neurons, lowering dopaminergic signaling in the brain.

The main indication is chorea associated with Huntington's disease, where tetrabenazine can decrease involuntary movements and improve function. It has been used off-label for other hyperkinetic conditions, such as tardive dyskinesia and tic disorders, with varying evidence by condition and region.

Tetrabenazine is taken orally and the dose is titrated to balance efficacy and tolerability. It is metabolized in the liver to active metabolites (HTBZs) and is processed mainly by CYP2D6; genetic variation in this enzyme affects drug exposure.

Safety concerns include sedation, fatigue, and dizziness, as well as psychiatric effects such as depression and suicidality, for which the drug carries boxed warnings in several places. Other adverse effects include parkinsonism‑like symptoms, dysarthria, nausea, weight change, and hypotension. Caution is advised in patients with a history of depression or hepatic impairment and when co-administered with other monoamine‑modulating drugs or MAO inhibitors.