A biologically active liver metabolite of procainamide is often measured; what is it?

A biologically active liver metabolite of procainamide is often measured; what is it?

• A. Phenobarbital
• B. Quinidine
• C. N-acetyl procainamide
• D. Lidocaine

Answer: (C)

Procainamide is processed by the liver into a pharmacologically active metabolite called N-acetylprocainamide. This metabolite, often measured in therapy, contributes to the antiarrhythmic effect and can accumulate in some patients (for example, slow acetylators or reduced renal function), influencing both efficacy and risk of toxicity. Monitoring NAPA levels helps tailor dosing to maintain effectiveness while avoiding adverse effects. The other substances listed are different drugs, not metabolites of procainamide.

Procainamide is processed by the liver into a pharmacologically active metabolite called N-acetylprocainamide. This metabolite, often measured in therapy, contributes to the antiarrhythmic effect and can accumulate in some patients (for example, slow acetylators or reduced renal function), influencing both efficacy and risk of toxicity. Monitoring NAPA levels helps tailor dosing to maintain effectiveness while avoiding adverse effects. The other substances listed are different drugs, not metabolites of procainamide.