Simultaneous quantification of mirabegron and vibegron in human plasma by HPLC-MS/MS and its application in the clinical determination in patients with tumors associated with overactive bladder

Mirabegron and vibegron, both newly identified beta-3 adrenergic agonists, have significantly improved the quality of life for patients suffering from overactive bladder. In order to comprehensively assess the plasma exposure levels of these agents, the development of a rapid and highly sensitive bioanalytical method becomes imperative. The primary objective of this study was to establish a robust high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the concurrent quantification of mirabegron and vibegron in human plasma. The analytes were extracted from a 100 μL plasma sample through protein precipitation, employing 300 μL of methanol. Subsequently, samples underwent separation and quantification using a Waters XBridge C18 column (2.1 × 100 mm, 3.5 µm), with a mobile phase consisting of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. The mass analysis was conducted using positive electrospray ionization (ESI+) operated in a multiple reaction monitoring (MRM) mode. The proposed method was meticulously validated in accordance with the guidelines set forth by the U.S. Food and Drug Administration (FDA) for bioanalytical method validation. The regression equations demonstrated exceptional linearity for both mirabegron (r² ≥ 0.994) and vibegron (r² ≥ 0.996) across the concentration range of 0.5 – 200 ng/mL. Furthermore, the assay exhibited accuracy (inter-day relative error ≤ 6.90%) and precision (inter-day coefficient of variation ≤ 8.88%). The average recoveries of the analytes were found to range from 81.94% to 102.02%, with mean matrix effects falling within the range of 89.77% to 110.58%. As a result, this method was deemed highly suitable for the precise determination of the concentrations of both mirabegron and vibegron in the context of therapeutic drug monitoring and bioequivalence studies.