Blood Quinidine Concentrations as a Guide in the Treatment of Cardiac Arrhythmias

Abstract

Blood quinidine determinations by the photofluorometric method were made in 30 patients with auricular fibrillation or flutter in whom conversion to sinus rhythm was attempted. Successful conversion occurred in 82 per cent of the patients, with a mean blood level of 5.9 mg./liter. Vomiting and, in one case, ventricular tachycardia were the most important toxic manifestations. Doses of 0.4 to 0.6 Gm. every two hours for five doses daily were usually adequate to obtain the average conversion blood level. The importance of the quantitative aspects of quinidine therapy and the relation of time, dose and concentration of quinidine in the blood are discussed.