Amiodarone--application and clinical pharmacology in atrial fibrillation and other arrhythmias.

Forty patients with atrial fibrillation (AF), 23 patients with ventricular extrasystoles (VES), and 11 patients with various arrhythmias (VA) were treated with amiodarone (0.2-0.6 g/day). Suppression of arrhythmia was 67.5% in AF, 78.2% in VES, and 81.8% in others with VA. Median age of converted patients was higher than that of nonconverted. The duration of AF before treatment was inversely related to drug efficacy. Average time needed for conversion was 6-8 days of treatment. Plasma amiodarone concentration at the day of conversion did not differ from that of nonconverted patients. Amiodarone concentration levels off after the 8th day of treatment, whereas that of the metabolite increases with time of treatment. Biologic half-life of plasma amiodarone after discontinuation of treatment varied, but was higher than 4 days. The percent of decline of the metabolite concentration was lower than that of the parent drug.