title: Simple and Sensitive UPLC-MS/MS Method for High-Throughput Analysis of Ibrutinib in Rat Plasma: Optimization by Box-Behnken Experimental Design.
abstract: Ibrutinib was the first Bruton's tyrosine kinase inhibitor that was approved by the U.S. Food and Drug Administration (FDA) for the treatment of mantle cell lymphoma, chronic lymphocytic leukemia, and waldenstrom macroglobulinemia. The aim of this study was to develop a UPLC-tandem MS method for the high-throughput analysis of ibrutinib in rat plasma samples. A chromatographic condition was optimized by the implementation of the Box-Behnken experimental design. Both ibrutinib and internal standard (vilazodone; IS) were separated within 2 min using the mobile phase of 0.1% formic acid in acetonitrile and 0.1% formic acid in 10 mM ammonium acetate in a ratio of 80+20, eluted at a flow rate of 0.250 mL/min. A simple protein precipitation method was used for the sample cleanup procedure. The detection was performed in electrospray ionization (ESI) positive mode using multiple reaction monitoring by ion transitions of m/z 441.16 > 84.02 for ibrutinib and m/z 442.17 > 155.02 for IS, respectively. All calibration curves were linear in the concentration range of 0.35 to 400 ng/mL (r2≥ 0.997) with a lower LOQ of 0.35 ng/mL only. All validation parameter results were within the acceptance criteria as per international regulatory guidelines. The developed assay was successfully applied in the pharmacokinetic study of a novel ibrutinib self-nanoemulsifying drug-delivery system formulation.