Different tissue distribution of paclitaxel with intravenous and intraperitoneal administration

Paclitaxel is considered to be suitable for disseminated cancer in the peritoneal cavity because of its high molecular weight and lipophilic characteristics. However, the difference in pharmacokinetics of paclitaxel after intraperitoneal (i.p.) and intravenous (i.v.) administration is not fully defined. Here, we investigated the tissue concentration of paclitaxel in various organs at various time points after i.p. or i.v. administration.

Paclitaxel (5 mg/kg) was administrated in an ear vein or in the abdominal cavity of rabbits. At 0.5, 6, 24, and 48 h after administration, the rabbits were sacrificed, and organs as well as peripheral blood were harvested. The serum and tissue concentrations of paclitaxel were measured by HPLC procedure.

The concentration of paclitaxel was high in the i.v. group at 0.5 h, whereas it was significantly higher in the i.p. group at 6 and 24 h. The AUC (area under the curve) was markedly higher in the omentum, mesenteric lymph nodes as well as ovary and stomach in the i.p. group.

Compared with i.v. administration, paclitaxel concentration was maintained at a high level in the whole body by i.p. administration. Repeated i.p. paclitaxel can produce more marked clinical effects than i.v. administration for metastatic lymph nodes and primary lesions as well as peritoneal dissemination.