Pharmacokinetic study of weekly administration dose of paclitaxel in patients with advanced or recurrent gastric cancer in Japan

Background. We aimed to clarify the relationship between the maximum tolerated dose and plasma concentration of paclitaxel in Japanese patients with gastric cancer on a weekly paclitaxel administration regimen. Methods. Thirty-three patients with advanced or recurrent gastric cancer were treated with escalating doses of paclitaxel, administered weekly, along with a fixed dose of 5-fluorouracil or cisplatin. Results. The plasma concentration of paclitaxel remained above 8.5 ng/ml for 24 h after administration. The mean area under the curve increased significantly with escalating dosage levels (R = 0.63; P < 0.001). At level 4, patients showing dose-limiting toxicity had a significantly higher plasma paclitaxel concentration than patients without it. Conclusion. The weekly administration of paclitaxel, for which a single dose is about one-third of the dose for a triweekly treatment regimen, is clinically feasible and appropriate in terms of toxicity and the maintenance of an effective plasma concentration.