A HPLC-fluorescence method for the quantification of abiraterone in plasma from patients with metastatic castration-resistant prostate cancer.

Abiraterone acetate is an oral prodrug of abiraterone, a selective inhibitor of CYP17, used for patients with metastatic castration-resistant prostate cancer (mCRPC). To date, a single liquid chromatographic-tandem mass spectroscopy method has been reported to assay abiraterone concentration in plasma from mCRPC patients. The aim of this study was to develop a simple and sensitive high performance liquid chromatographic (HPLC) method with fluorescence detection for quantification of abiraterone in plasma from mCRPC patients. After protein precipitation with acetonitrile and a liquid-liquid extraction with diethyl ether, abiraterone, and hydroxy-itraconazole (internal standard) were separated on a C8 Xterra(®) MS column using a mobile phase of acetonitrile and glycine buffer 88.4 mM (pH 9.0) (60:40, v/v). Samples were eluted isocratically at a flow rate of 0.9 ml/min throughout an 11-min run. Fluorescence wavelengths' excitation and emission were 255 and 373 nm, respectively. The calibration was linear in the range 1.75-50 ng/ml. Inter- and intraday imprecision were less than 3.5 and 7%, respectively. This method is simple, sensitive, and selective. This analytical method was successfully applied to determine the steady-state plasma exposure to abiraterone in mCRPC patients. This method can be used in routine clinical practice to monitor plasma abiraterone concentrations in mCRPC patients.