Which antipsychotic has the highest risk of causing QTc prolongation and sudden cardiac death, and is specifically contraindicated in patients with congenital long QT syndrome?
- A Clozapine
- B Haloperidol
- C Thioridazine ✓
- D Aripiprazole
Correct answer: C. Thioridazine
Explanation
Thioridazine carries the highest QTc prolongation risk among antipsychotics due to potent inhibition of cardiac hERG (IKr) potassium channels. It is now restricted to refractory schizophrenia as last-resort therapy and contraindicated in long QT syndrome, hypokalemia, and with other QT-prolonging drugs. Clozapine's main risks are agranulocytosis and myocarditis. Haloperidol prolongs QT but to a lesser degree. Aripiprazole has minimal QTc effect.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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