Kinetics of Disopyramide after Intravenous Infusion to Patients with Myocardial Infarction and Heart Failure

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Abstract
Total body clearance, half-life and volume of distribution of disopyramide (Norpace, Searle G.D.) was measured during a 6-8 h infusion to steady state in 24 patients with either congestive heart failure or acute myocardial infarction and compared to 11 patients without these diseases. All patients were given a bolus injection of 150 mg disopyramide followed by a continuous infusion of 18-24 mg/h. Serum concentration of disopyramide and its main dealkylated metabolite were determined by HPLC [high performance liquid chromatography]. The clearance in patients without myocardial infarction or congestive heart failure was 1.71 .+-. 0.60 ml/min per kg (.hivin.X .+-. SD), not significantly different from those who had earlier myocardial infarction, congestive heart failure or both. Half-life was 798 min in patients without heart failure, not significantly different from the values in the other groups. The ratio between disopyramide and its metabolite varied between 3-10. Of the steady state serum concentrations of disopyramide, 26% were outside the recommended therapeutic range (2-5 .mu.g/ml), but no adverse hemodynamic effects were observed in any of the patients. The suggested dosage regimen of disopyramide seems to result in a satisfactory response.