Procainamide

Abstract

Procainamide is a class la anti-arrhythmic used in a wide range of cardiac arrhythmias with properties similar to quinidine. The short duration of action and high incidence of side-effects generally limit its use to the acute control of arrhythmias where the less marked hypotensive action on intravenous administration relative to quinidine is an advantage. Grave hypotension and cardiac abnormalities are, however, major side-effects when procainamide is given too rapidly intravenously, and hypersensitivity reactions are an additional danger of long-term use. It is readily absorbed via the oral route, and acetylated in the liver to N-acetylprocainamide (acecainide) by enzymes which show a genetic polymorphism. There is therefore inter-subject variation in the production of N-acetylprocainamide which is an anti-arrhythmic in its own right and may represent a significant fraction of the drug in the circulation.