Altered pharmacokinetics of daunorubicin in rats with CCl4-induced hepatic injury.

PURPOSE The effect of CCl4-induced experimental hepatic injury (CCl4-EHI) on the pharmacokinetics of daunorubicin was investigated systemically in rats, in an attempt to elucidate the major determinants of the effect of CCl4-EHI on the pharmacokinetics of the drug. METHODS CCl4-EHI was induced in rats by a single intraperitoneal injection of CCl4 (1 mL/kg rat), and a 24 h fasting period. Daunorubicin was administered intravenously to control and EHI rats at a dose of 11.3 mg/mL/kg and the in vivo pharmacokinetics was studied. The in vitro uptake of the drug into isolated hepatocytes and canalicular liver plasma membrane (cLPM) vesicles, as well as the liver microsomal degradation of the drug, were also determined. RESULTS The area under the plasma concentration-time curve (AUC) of daunorubicin was increased by 1.6 times, resulting in a 34% decrease in the systemic clearance (CL) in rats with CCl4-EHI. The apparent biliary (CLbile) and urinary (CLurine) clearance of the drug were unchanged, whereas the AUC of daunorubicinol, the major metabolite of daunorubicin, was decreased by 66% in rats with CCl4-EHI. EHI seemed to affect the hepatobiliary elimination of the drug in several ways: the in vitro intrinsic sinusoidal uptake clearance was decreased by 20%; the in vitro intrinsic canalicular excretion clearance of the drug was increased by 1.7 times; and the in vitro liver microsomal degradation of daunorubicin was significantly retarded. CONCLUSIONS CCl4-EHI appears to impair the hepatic metabolism of daunorubicin, thereby decreasing the CL and increasing the AUC of daunorubicin.