A 58-year-old man with schizophrenia treated with fluphenazine decanoate for 15 years develops involuntary chewing, lip smacking, and choreoathetoid movements of the hands. The movements persist after the antipsychotic is stopped for 3 months. Which agent targets the underlying mechanism of this disorder?

• A Levodopa-carbidopa
• B Valbenazine, a vesicular monoamine transporter 2 inhibitor ✓
• C Trihexyphenidyl
• D Haloperidol, to suppress the abnormal movements

Explanation

This is tardive dyskinesia, thought to result from dopaminergic receptor supersensitivity in the basal ganglia after chronic D2 blockade. VMAT2 inhibitors such as valbenazine and deutetrabenazine deplete presynaptic monoamine stores, reducing dopamine release, and are the approved treatments shown to reduce movement severity. Trihexyphenidyl treats acute dystonia and parkinsonism but can worsen dyskinesia. Adding more dopamine blockade masks symptoms temporarily while worsening the supersensitivity, and levodopa would aggravate the movements.

Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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