A patient on long-term procainamide for ventricular arrhythmias develops arthralgia, myalgia, and pleuritic chest pain with a positive ANA. This drug-induced lupus-like syndrome is most common in which pharmacogenomic subgroup?
- A Rapid acetylators of N-acetyltransferase
- B Slow acetylators of N-acetyltransferase ✓
- C CYP2D6 poor metabolizers
- D CYP2C19 ultra-rapid metabolizers
Correct answer: B. Slow acetylators of N-acetyltransferase
Explanation
Procainamide is metabolized by N-acetyltransferase. Slow acetylators accumulate the parent drug and are at higher risk of procainamide-induced lupus. Hydralazine-induced lupus also shows this pharmacogenomic pattern. CYP2D6 and CYP2C19 polymorphisms are relevant to metoprolol and clopidogrel metabolism, not procainamide lupus.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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