Aim and Objective: An analytical method for the determination of mobocertinib, an
investigational tyrosine kinase inhibitor, was developed and optimized by high-performance liquid
chromatography-tandem mass spectrometry (LC-MS/MS) in rat plasma.
Materials and Methods: Plasma samples were pretreated by the protein precipitation method with
a methanol solution of osimertinib as the internal standard (IS). Chromatographic separation was
performed using an Inertsil ODS-3 column (50 mm × 4.6 mm, I.D. 5 μm) with the temperature
maintained at 40°C. The mobile phase consisted of water (containing 0.1% formic acid) and
methanol in a gradient mode at a flow rate of 0.5 mL/min. Mass spectrometric detection was
carried out in the selected reaction monitoring (SRM) mode with positive electrospray ionization,
and the mass transitions of mobocertinib and osimertinib were m/z 587.01 → 71.88 and m/z
499.80 → 71.94, respectively. The method was validated in terms of selectivity, linearity, accuracy
and precision, extraction recovery and matrix effect, stability and carryover as per the guidelines
for bioanalytical method validation (FDA, 2018). The method was applied to the pharmacokinetic
study of mobocertinib in rats by oral gavage at the doses of 2, 6, and 18 mg/kg. A total of 216
plasma samples from 18 rats were analyzed.
Results: The results showed good linearity over the range of 1-1000 ng/mL (R2 = 0.9957). The
intra-batch accuracy was within 94.65-102.59% and the precision was within 5.49-10.46%. The
inter-batch accuracy was within 97.08-102.25% with a precision of 7.54-10.13%. The extraction
recovery and matrix factor were acceptable for the bioanalysis of mobocertinib. Additionally,
mobocertinib was found to be stable under the detected conditions. Mobocertinib showed linear
pharmacokinetic characteristics following oral administration to rats at 2.0-18.0 mg/kg.
Conclusion: The developed and validated method was successfully employed in the
pharmacokinetic study in rats following oral administration of mobocertinib at the doses of 2, 6,
and 18 mg/kg.