Abstract
A highly selective, sensitive, and reliable high-performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of a novel type of dopamine receptor antagonist LE300 and its N-methyl metabolite in mouse sera. LE300, its N-methyl metabolite, and verapamil (an internal standard) were detected using excitation and emission wavelengths of 275 and 340 nm, respectively. HPLC analysis using a deproteinization procedure was performed by injecting an aliquot of the supernatant into the chromatographic system. Chromatographic separation was achieved on a reversed-phase Spherisorb Cyano (CN) column with a mobile phase consisting of acetonitrile:50 mM phosphate buffer pH 3.5 (70:30, v/v) pumped at a flow rate of 1.0 mL min(-1). Regression analyses showed excellent linearity (r = 0.999) for concentrations of LE300 ranging from 4 to 500 ng mL(-1) and for concentrations of its N-methyl metabolite of 6-600 ng mL(-1). The HPLC-FLD method had limits of detection of 1.6 ng mL(-1) for LE300 and 2.4 ng mL(-1) for its N-methyl metabolite in mouse sera. The precision results, expressed as the intraday and interday relative standard deviation (RSD) values, ranged from 0.65 to 2.85 % (repeatability) and from 0.37 to 2.62 % (intermediate precision) for LE300 and its N-methyl metabolite, respectively; these values are in line with ICH guidelines. The assay was successfully applied in a pharmacokinetic study. The mean values of T (max) and C (max) were 2 h and 25.03 +/- A 5.60 ng mL(-1) for LE300 and 3 h and 19.92 +/- A 2.88 ng mL(-1) for its N-methyl metabolite, respectively.