A 55-year-old man with schizophrenia on haloperidol for 12 years develops repetitive lip smacking and choreoathetoid movements of the tongue. Haloperidol is stopped and switched to clozapine, but movements persist. Which drug directly targets the vesicular monoamine transporter to reduce these movements?
- A Tetrabenazine ✓
- B Propranolol
- C Amantadine
- D Benztropine
Correct answer: A. Tetrabenazine
Explanation
Tardive dyskinesia is now specifically treated with VMAT2 inhibitors such as tetrabenazine, deutetrabenazine, and valbenazine. By blocking vesicular monoamine transporter 2, they deplete presynaptic dopamine stores and reduce dopaminergic output from striatal neurons. Benztropine is anticholinergic and may actually worsen dyskinesias. Amantadine has modest antidyskinetic effect via glutamate mechanisms but does not act on VMAT2. Propranolol treats akathisia, not choreoathetosis.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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