The effect of hepatic disease on the disposition of moricizine in humans.

The pharmacokinetics of moricizine and two of its metabolites, moricizine sulfoxide and phenothiazine-2-carbamic acid ethyl ester sulfoxide, were studied in healthy control subjects and in patients with chronic liver disease (cirrhosis). Moricizine disposition was significantly altered by hepatic cirrhosis. Compared to healthy subjects, the hepatic disease patients had an increased Cmax (59%), an increased t1/2 (141%), and a reduced plasma clearance (71%). Additionally, small but statistically significant increases were observed for tmax and the fraction of moricizine not bound to plasma proteins in patients with hepatic disease. The elimination of both moricizine metabolites was also altered by hepatic dysfunction as indicated by significantly prolonged terminal half-lives. Furthermore, there was a reduction in the conversion of moricizine to moricizine sulfoxide. Both hepatic blood flow and hepatic metabolizing capacity were assessed in all subjects and patients by administration of indocyanine green and antipyrine, respectively. Indocyanine green and antipyrine plasma clearances were decreased by 38 and 51%, respectively, indicating that both functions were diminished by hepatic cirrhosis. We conclude that the moricizine dose required for arrhythmia patients with hepatic disease should be lower, and perhaps, the dosing frequency should be less than in patients with normal liver function.