Therapeutic drug monitoring of paclitaxel (Zisu) in cancer patients.

We monitored the therapeutic drug paclitaxel (Zisu) and studied its anticancer activity and side effects in 11 cancer patients. After intravenous infusion of 135 to 185 mg/m2 of paclitaxel, Cmax ranged from 2.17 to 9.17 mg/L and AUC ranged from 4.37 to 16.01 mg/h/L. A significant individual difference in pharmacokinetic parameters was found. Among the 11 patients, 6 achieved a partial remission and one patient had a mild response. The Cmax of the patients who achieved PR and MR was higher in comparison to the patients with no response. In 4 of the 6 PR patients, Cmax was above 4.38 mg/L. In four of the NR patients, Cmax was equal to or below 4.04 mg/L. These results suggested a relationship between Cmax and the cancer response rate. No significant relationship could be found between Cmax and the nadir of the white blood cells and platelets.