Bioanalytical method for the simultaneous quantification of irinotecan and its active metabolite SN-38 in mouse plasma and tissue homogenates using HPLC-fluorescence

A simple and rapid bioanalytical method was developed for the simultaneous quantification of irinotecan and SN-38 in mouse plasma and tissue homogenates using High-Performance Liquid Chromatography with Fluorescence detection (HPLC-FL). Camptothecin was used as internal standard and protein precipitation with acetonitrile-methanol (1:1, v/v) followed by acidification with 0.5 M hydrochloric acid was used for sample pre-treatment. The analytes and the internal standard were detected using an excitation and emission wavelength of 368 and 515 nm, respectively. The linearity, selectivity, accuracy and precision, carry-over, limit of detection and lower limit of quantification of the method are described. The method was linear from 7.5 to 1500 ng/mL for irinotecan and from 5 to 1000 ng/mL for SN-38. For all matrices, the accuracy bias and precision variation were within ±15% and ≤15%, respectively. This method was successfully applied to study the pharmacokinetics of irinotecan and SN-38 using in vivo mouse models