Among antipsychotic drugs, which agent carries the highest risk of dose-dependent QT prolongation and torsades de pointes?
- A Fluphenazine
- B Haloperidol given orally
- C Thioridazine ✓
- D Trifluoperazine
Correct answer: C. Thioridazine
Explanation
Thioridazine blocks cardiac hERG potassium channels more strongly than any other antipsychotic and produces dose-related QT prolongation with a documented risk of torsades and sudden death, leading regulators to restrict its use to refractory schizophrenia after two other agents have failed. Intravenous haloperidol prolongs QT, but oral haloperidol carries far less cardiac risk than thioridazine, which kills option B.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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