Tardive dyskinesia developing after years of antipsychotic therapy is treated with a drug whose mechanism is selective depletion of presynaptic dopamine stores. This agent is:

• A Propranolol, a beta-adrenergic antagonist
• B Valbenazine, a vesicular monoamine transporter 2 inhibitor ✓
• C Levodopa-carbidopa, a dopamine precursor
• D Trihexyphenidyl, a central muscarinic antagonist

Explanation

Valbenazine and deutetrabenazine inhibit VMAT2, the transporter that packages dopamine into synaptic vesicles, thereby depleting releasable presynaptic dopamine and reducing involuntary choreiform movements of tardive dyskinesia. Trihexyphenidyl treats drug-induced parkinsonism, not dyskinesia, and propranolol helps akathisia. Levodopa would worsen dyskinesias. Note that tetrabenazine itself can worsen depression through monoamine depletion, a limitation shared by this entire class.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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