Determination of ulixertinib in mice plasma by LC-MS/MS and its application to a pharmacokinetic study in mice.

A sensitive, specific and rapid LC-ESI-MS/MS method has been developed and validated for the quantification of ulixertinib in mice plasma using phenacetin as an internal standard (I.S.) as per regulatory guidelines. Sample preparation was accomplished through a protein precipitation procedure with acetonitrile:methanol mixture. Chromatographic separation was performed on Atlantis dC18 column using a binary gradient using mobile phase A (0.2% formic acid in water) and B (acetonitrile) at a flow rate of 0.60mL/min. Elution of ulixertinib and I.S. occurred at ∼1.07 and 1.20min, respectively. The total chromatographic run time was 2.5min. A linear response function was established in the concentration range of 1.58-2054ng/mL. The intra- and inter-day accuracy and precisions were in the range of 2.11-11.8 and 5.80-11.4%, respectively. This novel method has been applied to a pharmacokinetic study in mice.