Determination of brexpiprazole Concentration in human Plasma by UHPLC-MS/MS and Its bioequivalence study

OBJECTIVE To establish a fast and sensitive UHPLC-MS/MS method for determination of brexpiprazole in human plasma and to investigate the bioequivalence between 2 formulations of tablets. METHODS Waters Acquity UPLC BEH C₁₈ (2.1 mm×50 mm, 1.7 μm) column was used with the mobile phase consisting of 0.1% formic acid water(A) and acetonitrile-methanol(50∶50, containing 0.1% formic acid)(B) in gradient elution. The flow rate was controlled at 0.4 mL·min^-1 with the injection volume of 2 μL and the column temperature was set at 40 ℃. A mass spectrometer equipped with electrospray ionization source was used and brexpiprazole(m/z 434.2→273.2) was monitored in positive ion MRM mode, with brexpiprazole-d₈ (m/z 442.4→281.3) as internal standard, ion source was ESI source. After addition of internal standard, plasma protein was precipitated by methanol, and supernatants were detected after dilution. RESULTS Brexpiprazole was linear in the range of 0.2-50 ng·mL^-1 and the lower limit of quantification was 0.2 ng·mL^-1. The intra-day and inter-day precision CV of quality-control samples was ≤5.0%, and the accuracy was in the range of -1.7%-5.5% in terms of relative error. Recovery rate, specificity, matrix effect and stability met the guiding principles and criteria of NMPA. The method was successfully applied to a bioequivalence study of brexpiprazole orally disintegrating tablets containing 2 mg in healthy volunteers. The average C_max under fasting and fed condition of the reference tablet were 19.62 and 20.83 ng·mL^-1. The average C_maxunder fasting and fed condition of the test tablet were 21.68 and 19.74 ng·mL^-1. CONCLUSION The method is sensitive and simple in process, and can produce well chromatographic performance. The test brexpiprazole orally disintegrating tablet is bioequivalent to the reference tablets.