Abstract: Aim To research the effects of anticarcinogens on the pharmacokinetics of on-dansetron. Methods The pharmacokinetics of ondansetron was studied in 21 cases of primary lung carcinoma treated with methotrexate, 5-fluorouracil, lomustine, cyclophosphamide plus vincristine, and cis-platin. Before and within chemotherapy, ondansetron concentrations in plasma were determined by a reversed-phase high performance liquid chromatography. The data obtained were fitted with PKBP-N1 pharmacokinetic program. Results The plasma drug concentration-time course conformed to a two-compartment open model with a rapid absorption both before and after chemotherapy. Because methotrexate and lomustine were taken in single/large dose schedule, they did not cause the pharmacokinetic parameters of ondansetron to change markedly, but T_1/2β was prolonged for about 0.5h. Other three chemother apiescaused the parametersof ondansetron to changemarkedly, except T_1/2ka and T_max, T_1/2β was prolonged for 1h T_1/2α hada irregular change, and C_max and AUC were remarkably increased.But ondansetronwas stored up in patient's body after taken with multi-dose.Conclusion The test points out that regulating rationaly medicine plan is necessary when ondansetron is used within sustained chemotherapy.

Key words: ondansetron;pharmacokinetic;anticarcinogen