Disopyramide: six years' experience

Disopyramide and N-monodesalkyl disopyramide in serum and breast milk

Maternal serum and breast milk were obtained to determine the concentration of disopyramide (DP) and its metabolite N-monodesalkyl disopyramide (NMD) from a woman requiring antidysrhythmic drug therapy. Infant serum and urine were also obtained for drug concentrations. DP 450 mg tid resulted in peak maternal serum concentrations of 4.0 micrograms/mL and 2.2 micrograms/mL for DP and NMD, respectively. Breast milk concentrations averaged 1.06 and 6.24 times the serum levels for DP and NMD, respectively. No DP was measurable in the infant's serum except for cord blood, which contained 0.7 micrograms/mL DP, 26 percent of simultaneous maternal concentration, and 0.9 micrograms/mL NMD, which represented 43 percent of the maternal concentration. Infant urine collected over an eight-hour period contained 3.3 micrograms/mL of DP and 3.7 micrograms/mL of NMD.

Long-term therapy with disopyramide phosphate: side effects and effectiveness

In this study, the safety and efficacy of long-term therapy with disopyramide phosphate were evaluated in 40 patients with documented, recurrent, symptomatic tachyarrhythmias. Twenty-one (53%) of the patients had organic heart disease, and nine of these patients had compensated congestive heart failure. The tachyarrhythmias which were treated were paroxysmal supraventricular tachycardia (21 patients), paroxysmal atrial fibrillation (six patients), and paroxysmal ventricular tachycardia (13 patients). In each patient there was evidence, from continuous ECG monitoring or electrophysiologic testing, that disopyramide would be effective therapy, and each patient was able to tolerate disopyramide (no side effects or tolerable side effects) during an initial trial period of 1 to 2 weeks. Dosages of disopyramide were 400 to 1600 mg/day (994 +/- 320 mm/day). During long-term therapy, side effects were reported by 28 (70%) of the patients. The side effects were usually anticholinergic, and were usually a continuation of side effects noted during the initial trial period. None of the patients had idiosyncratic reactions to disopyramide. Most of the patients found side effects to be tolerable; however, in seven patients it was necessary to discontinue disopyramide after 1 to 8 (6 +/- 3) months. Actuarial incidence of intolerable side effects was 21 +/- 7% at 12 months. Nine (22%) of the 40 patients had symptomatic recurrences of tachyarrhythmia after 3 to 32 (15 +/- 9) months of therapy. Actuarial incidence of drug ineffectiveness was 32 +/- 10% at 24 months. Disopyramide was both effective and tolerated in 24 (60%) of the patients, who were followed for 2 to 64 (23 +/- 16) months.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of low oral doses of disopyramide and amiodarone on ventricular and atrial arrhythmias of chagasic patients with advanced myocardial damage

Low-dose (7 mg/kg per day) disopyramide administration to arrhythmic chagasic patients decreased the frequency of ventricular extrasystoles in 4 of 17 patients (24%) and suppressed most complex ventricular arrhythmias in 12 of 15 patients (80%). This assessment was made from 72-h continuous Holter monitoring recorded during the course of this double blind, placebo-controlled randomized crossover study. Seven patients (41%) complained of anticholinergic side effects, but no contractile or conduction system depression was seen. Amiodarone (200 mg) given on a single blind, placebo-controlled basis to 9 of these patients reduced the frequency of ventricular extrasystoles in 6 of 9 patients (67%) and suppressed complex ventricular ectopy in 6 of 7 patients (85%). One patient was unable to tolerate this drug (11%). Both drugs seemed less effective in controlling supraventricular arrhythmias, although disopyramide eliminated paroxysms of supraventricular tachycardia in 9 of 13 (69%) and amiodarone in all 6 patients with this arrhythmia. Amiodarone appears to be a better antiarrhythmic drug for chagasic patients, due to its greater effectiveness and lower incidence of side effects.