Efficacy of oral and intravenous indecainide in ventricular arrhythmias.

To evaluate the efficacy of oral and intravenous indecainide, a new class IC antiarrhythmic agent, 3 separate protocols were performed in patients with benign or potentially lethal ventricular arrhythmias. An open-label intravenous trail in 10 patients was conducted using a dose of 1.7 mg/kg/min under constant monitoring. An oral short-term in-hospital trial in 20 patients (8 patients entered directly from the intravenous short-term trial) was conducted using a single-blind placebo dose titration protocol in which 50 mg of indecainide every 8 hours was increased at 3-day intervals to 75 mg, and then 100 mg every 8 hours depending on the observed change in ventricular arrhythmia frequency by Holter monitoring. Finally, an outpatient long-term oral trial was conducted in 17 of the 20 patients who completed the inpatient oral short-term trail. Two of the 10 patients from the inpatient intravenous trail did not enter the oral trial, because a proarrhythmic response developed in 1 and because of a lack of efficacy in the other. During the inpatient oral trial, 17 of 20 patients (85%) responded to indecainide and entered the long-term phase. Two of these patients were removed from the trial because of lack of efficacy at 3 and 10 months, respectively. In the oral therapy protocols, minor side effects of the central nervous system occurred in 4 of 17 patients (24%). Six of 20 patients (30%) each had more than a 25% increase in PR and QRS duration that was not associated with higher degrees of block.(ABSTRACT TRUNCATED AT 250 WORDS)