ABSTRACT
Tetrabenazine is excreted in breast milk. Avoid prescribing tetrabenazine pharmacotherapy to women who are breast-feeding. If tetrabenazine pharmacotherapy is required, breast-feeding probably should be discontinued. Tetrabenazine interferes with the vesicular storage of biogenic amines, including dopamine, norepinephrine, and serotonin. Hydroxytetrabenazine appears to be the principal active metabolite of tetrabenazine that elicits its effects primarily within the brain. Tetrabenazine also displays antidopaminergic activity within the corpus striatum. Tetrabenazine is absorbed erratically from the GI tract following oral ingestion and is subject to extensive first-pass hepatic metabolism. Virtually all of the oral dose that is absorbed is metabolized to the principal active metabolite, hydroxytetrabenazine. Tetrabenazine pharmacotherapy exacerbates the signs and symptoms of Parkinson’s disease and, therefore, significantly reduces the therapeutic action of levodopa. Tetrabenazine pharmacotherapy commonly has been associated with depression, drowsiness, fatigue, parkinsonian signs and symptoms, and weakness. Signs and symptoms of tetrabenazine overdosage include drowsiness, hypotension, hypothermia, and sweating.
