Safety of multiple bolus loading of intravenous disopyramide

Although a single intravenous bolus of disopyramide is an effective antiarrhythmic, side effects occur in some patients. We tested the safety of multiple bolus loading for intravenous disopyramide in 10 patients with frequent premature ventricular beats. Concurrent with a 1.0 mg/kg/hr infusion, a bolus of 0.5 mg/kg of disopyramide was given over 5 minutes. Up to three additional boluses were given 5 minutes after the first bolus unless a 50% reduction in premature ventricular beats or side effects occurred. The infusion was continued for 3 hours and was then decreased to 0.4 mg/kg/hr for 15 hours. All patients had a 50% reduction in premature ventricular beats and attained therapeutic blood levels. Three patients with a history of controlled congestive heart failure developed either hypotension or pulmonary edema. Hypotension and pulmonary edema following intravenous disopyramide is more related to the pharmacology of the drug than to the loading scheme employed.