A 72-year-old woman with chronic kidney disease develops cardiac arrest. The cardiac monitor shows polymorphic ventricular tachycardia consistent with Torsades de Pointes. Which drug is the most appropriate initial treatment?

• A Amiodarone
• B Lidocaine
• C Procainamide
• D Magnesium sulfate ✓

Explanation

Magnesium sulfate is the first-line drug for Torsades de Pointes, even if serum magnesium levels are normal. It stabilizes the myocardial cell membrane and shortens the QT interval. Procainamide and amiodarone are contraindicated because they prolong the QT interval and can worsen the arrhythmia. Lidocaine is a second-line agent but is less effective than magnesium for this specific polymorphic ventricular tachycardia.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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