CLINICAL PROGRESS Procaine Amide A Review

PROCAINE amide was introduced for the treatment of cardiac arrhythmias 6 years ago. Since then a number of studies with the compound have been reported. A review of the results may help in appraising the value of the drug as a therapeutic agent. The first step toward the development of procaine amide was taken when Mautz, ' in 1936, showed that procaine, applied directly to the myocardium of animals, elevated the threshold of ventricular muscle to electric stimulation. Beck and Mautz2 then demon-strated that the topical application of procaine in surgery involving stripping of the peri-cardium, reduced the occurrence of ventricular and atrial extrasystoles. In 1946, Burstein3 reported that procaine was an effective anti-arrhythmic agent when injected intrave-nously, and he employed it in anesthetized patients prophylactically as well as thera-peutically. Although of undoubted effective antiarrhythmic activity, procaine has limited use in the general treatment of arrhythmias because of its central stimulatory effects, which restrict its use to anesthetized patients. A study on the fate of procaine in man showed that the drug after intravenous injec-tion was enzymatically hydrolysed in plasma with extreme rapidity to para-aminobenzoic acid and diethylaminoethanol.4 The rapid hydrolysis of procaine suggested that its anti-arrhythmic action might be mediated through one of the metabolites. Para-aminobenzoic acid was found to have no antiarrhythmi