Liquid Chromatography Combined With Electrospray Ionization Tandem Mass Spectrometry for the Determination and Identification of AZD5462 and Its Metabolites in Rat Plasma

AZD5462, a human RXFP1 agonist, which is undergoing clinical development for the treatment of heart failure. The aim of this study was to develop an ultra-high-performance liquid chromatography-tandem mass spectrometric method for the determination of AZD5462 in rat plasma. After precipitated with acetonitrile, the sample was analyzed on a BEH C₁₈ column using 0.1% formic acid and acetonitrile as mobile phase with a gradient elution at 40°C within 2 min. The assay showed excellent linearity in the range of 0.1-1000 ng/mL with the correlation coefficient more than 0.995. The precision, accuracy, matrix effect, recovery, and stability met all requirements for the quantitation in plasma samples. The validated method has been further applied to the pharmacokinetic study of AZD5462 in rats. In addition, the metabolism of AZD5462 in rat was investigated by a liquid chromatography-high resolution mass spectrometry. In rat liver microsomes, four metabolites were identified based on their accurate mass and fragment ions. In rat plasma, one glucuronide conjugate was identified. The metabolic pathways of AZD5462 include oxygenation and glucuronidation. This study is the first report on the pharmacokinetics and metabolism of AZD5462, which would provide insights into the effectiveness and toxicity of this drug candidate.