Pharmacokinetics of intraperitoneal docetaxel and S-1 in patients with gastric cancer with peritoneal carcinomatosis

e15672 Background: One of the most causes of death from gastric cancer is peritoneal cartinomatosis. Intraperitoneal docetaxel infusion is expected to be a new strategy for a treatment of peritoneal carcinomatosis. The purpose of this study is to evaluate the plasma and peritoneal pharmacokinetic of intraperitoneal docetaxel infusion in combination with oral administration of S-1. Methods: Eight patients with peritoneal carcinomatosis of advanced gastric cancer were enrolled. Docetaxel was dissolved in an isotonic saline to a final 1 liter solution and administered in 2 hour via an implanted intraperitoneal catheter at dosage of 40mg/m2. Five of eight patients were administered S-1 orally at dosage of 80mg/m2. Blood and peritoneal fluid were collected before administration, on completion of the docetaxel infusion(hour 0) and at hours 1,2,4,6,12,24,48,and 72 after completion of the infusion of the docetaxel. Plasma and peritoneal fluid concentrations of docetaxel and 5FU were evaluated. Results: The mean peak peritoneal and plasma concentrations of docetaxel were 18.6×103 ng/ml (at hour 0) and 45 ng/ml (at hour 0 to 2), respectively. The peritoneal concentrations of docetaxel were remained even after 24 and 72 hours (24 hours: 1150ng/ml, 72 hours: 74ng/ml). In seven out of eight patients, plasma concentrations of docetaxel were disappeared after 24 hours, but in only one patient with severe ascites, concentration of plasma docetaxel at hour 24 could be obtained (20 ng/ml). The mean peritoneal and plasma areas under the curves (AUC) of doceta×el were 141x103 ng/ml×hr and 480 ng/ml×hr, respectively. The mean peritoneal concentrations of 5FU kept over 60% of plasma concentrations (plasma: 164.3ng/ml, peritoneal: 105ng/ml). Conclusions: Intaperitoneal docetaxel kept relatively high concentrations even after 72hours. 5FU concentrations were well transfered in peritoneal fluid from plasma via oral S-1 administration. Intraperitoneal docetaxel in combination with S-1 orally may be a useful regimen to the patients with carcinomatosis of advanced gastric cancer. No significant financial relationships to disclose.