QUANTITATIVE-ANALYSIS OF TOREMIFENE METABOLITES IN BIOLOGICAL SPECIMENS USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Toremifene is a triphenylethylene derivative that is currently undergoing Phase I-III clinical trials for antineoplastic activity. Toremifene has also shown chemosensitizing activity in multidrug resistant cancer cells. In the present study, we developed a modified HPLC assay which allows for separation, and quantification of toremifene metabolites in biological specimens. Plasma samples containing various quantities of toremifene metabolites were spiked with an internal standard (nafoxidine), extracted with 2% butanol in hexane, and irradiated with high intensity ultraviolet light (254 nm). Aliquots of the extracted plasma components were injected onto a C18 reverse phase column and eluted isocratically with a mobile phase of 7% water and 0.18% triethylamine in methanol. Fluorescence of toremifene metabolites, and internal standard was measured at an excitation wavelength of 266nm. The sensitivity of this assay was approximately 20 ng/mL for each metabolite. Linearity was achieved for all the compounds with correlation coefficients of greater than 0.99. The assay presented is highly specific, very sensitive, and demonstrates reproducible linearity throughout a wide range of clinically relevant plasma concentrations. © 1990, Taylor & Francis Group, LLC. All rights reserved.