Simultaneous Determination of Ibrutinib, Dihydroxydiol Ibrutinib, and Zanubrutinib in Human Plasma by Liquid Chromatography-Mass Spectrometry/Mass Spectrometry

Background: Ibrutinib and zanubrutinib are Bruton tyrosine kinase inhibitors used to treat mantle cell lymphoma, chronic lymphocytic leukemia, and small lymphocytic lymphoma. Dihydroxydiol ibrutinib (DHI) is an active metabolite of the drug. A liquid chromatography–tandem mass spectrometry method was developed to detect ibrutinib, DHI, and zanubrutinib in human plasma. Methods: The method involved a protein precipitation step, followed by chromatographic separation using a gradient of 10 mM ammonium acetate (containing 0.1% formic acid)–acetonitrile. Ibrutinib-d5 was used as an internal standard. Analytes were separated within 6.5 minutes. The optimized multiple reaction monitoring transitions of m/z 441.1 → 304.2, 475.2 → 304.2, 472.2 → 455.2, and 446.2 → 309.2 were selected to inspect ibrutinib, DHI, zanubrutinib, and the internal standards in positive ion mode. Results: The validated curve ranges included 0.200–800, 0.500–500, and 1.00–1000 ng/mL for ibrutinib, DHI, and zanubrutinib, respectively. The precisions of the lower limit of quantification of samples were below 15.5%, the precisions of the other level samples were below 11.4%, and the accuracies were between −8.6% and 8.4%. The matrix effect and extraction recovery of all compounds ranged between 97.6%–109.0% and 93.9%–105.2%, respectively. The selectivity, accuracy, precision, matrix effect, and extraction recovery results were acceptable according to international method validation guidelines. Conclusions: A simple and rapid method was developed and validated in this study. This method was used to analyze plasma concentrations of ibrutinib and zanubrutinib in patients with mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, or diffuse large B-cell lymphoma. The selected patients were aged between 44 and 74 years.