Altered pharmacokinetics of paclitaxel in experimental hepatic or renal failure.

Purpose: The aim of this study was to investigate the effect of hepatic or renal insufficiency on the pharmacokinetics of paclitaxel in rats.

Methods: Rats were treated with carbon tetrachloride (CCl4; 0.5 ml/kg) to induce hepatic failure or were subjected to 5/6 nephrectomy (5/6 Nx) to induce renal failure. Paclitaxel (3 mg/kg) was administered intravenously or intraportally. Testosterone 6beta-hydroxylase activity, which is a marker of CYP3A activity, was measured in rat liver microsomes from CCl4-treated or 5/6 Nx rats.

Results: After paclitaxel was administered intravenously, total body clearance was significantly reduced by 73% and 34% relative to each control value in CCl4-treated and 5/6 Nx rats, respectively (control, 1.82+/-0.42 vs. CCl4-treated, 0.49+/-0.11; sham, 1.54+/-0.07 vs. 5/6 Nx, 1.01+/-0.12 L h(-1) kg(-1); mean+/-SE, n = 5 to 6). Testosterone 6beta-hydroxylase activity was reduced by 92% and 59% relative to each control value in rat liver microsomes from CCl4-treated and 5/6 Nx rats, respectively. After the intraportal administration of paclitaxel, apparent clearance was reduced by 85% relative to control value in rats with hepatic failure, while that in rats with renal failure was the same as the reduction in systemic clearance.

Conclusions: These results suggested that not only hepatic failure but also renal failure could modify the pharmacokinetics of paclitaxel in vivo.