Procainamide is associated with which drug-induced condition?

• A. Drug-induced lupus erythematosus with antihistone antibodies
• B. Cinchonism
• C. Torsades de pointes
• D. Anticholinergic effects

Answer: (A)

Drug-induced lupus erythematosus is a known adverse effect of certain medications, including procainamide. The hallmark is an autoimmune reaction that resembles lupus but is driven by antihistone antibodies rather than the anti–double-stranded DNA antibodies seen in idiopathic SLE. With procainamide, risk increases with longer therapy and higher cumulative dose, and slow acetylators are especially susceptible. Clinically it presents with lupus-like symptoms such as arthralgias and fever, sometimes with serositis, and typically improves after stopping the drug. While other options list effects that can occur with various antiarrhythmics (cinchonism with quinidine; torsades de pointes from QT prolongation; anticholinergic effects with some agents), the distinctive and most characteristic association for procainamide is drug-induced lupus with antihistone antibodies.