title: A limited sampling model for estimating pharmacokinetics of CPT-11 and its metabolite SN-38.
abstract: The objective of this study was to develop a limited sampling model (LSM) to estimate the area under the curve (AUC) of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) and that of 7-ethyl-10-hydroxycamptothecin (SN-38) as predictive pharmacokinetic variables for leukopenia and episodes of diarrhea induced by CPT-11 administration. The model was developed with a training set consisting of pharmacokinetic studies in 36 patients who received a 90-min i.v. infusion of CPT-11 at a dose of 100 mg/m2. A multiple regression analysis of CPT-11 or SN-38 concentrations observed at each time point in the training set was used to predict the AUC of CPT-11 or SN-38. The final sampling models using only two time points were: AUCCPT-11 = 3.7891*C2.5 + 14.0479*C13.5 + 1.5463 AUCSN-38 = 0.5319*C2.5 + 19.1468*C13.5 + 72.7349 where C2.5 and C13.5 are the plasma concentration of CPT-11 (micrograms/ml) or SN-38 (ng/ml) at 2.5 and 13.5 h after the initiation of CPT-11 infusion, respectively. The models were validated prospectively on a separate test data set of 12 patients receiving the same dose of CPT-11 investigated in a previous study. Validation of the final LSM on the test data set gave values of root mean square error (RMSE) of 12.72% and 5.97% for the AUC of CPT-11 and that of SN-38, respectively. The model can be used to monitor the AUCs of both CPT-11 and SN-38 for the early prediction of toxicities and to establish a pharmacokinetically based dose modification strategy for safe administration of CPT-11.
authors.affiliation: Department of Medicine, National Cancer Center Hospital East, Chiba.
authors.forename: Y
authors.initials: Y
authors.lastname: Sasaki
authors.forename: S
authors.initials: S
authors.lastname: Mizuno
authors.forename: H
authors.initials: H
authors.lastname: Fujii
authors.forename: T
authors.initials: T
authors.lastname: Ohtsu
authors.forename: H
authors.initials: H
authors.lastname: Wakita
authors.forename: T
authors.initials: T
authors.lastname: Igarashi
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: I
authors.initials: I
authors.lastname: Sekine
authors.forename: Y
authors.initials: Y
authors.lastname: Miyata
authors.forename: N
authors.initials: N
authors.lastname: Saijo
mesh_terms: D000328:Adult; D000368:Aged; D000972:Antineoplastic Agents, Phytogenic / Q000097:blood / Q000493:pharmacokinetics*; D001800:Blood Specimen Collection; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011446:Prospective Studies; D012044:Regression Analysis
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002166:Camptothecin