A specific and linear liquid chromatography and tandem mass spectrometry method was developed for the quantitation of larotrectinib in plasma. The liquid–liquid extraction process with acetonitrile (ACN) and methanol in a 50:50 ratio was processed for drug isolation from the sample plasma. Chromatographic elution was processed on C18-Phenominex reverse phase (2.1 × 50 mm, 1.70 μ) column. Analyte elution was accomplished with an isocratic system of solvents having ACN, methyl alcohol, and 0.1% formic acid in the ratio of 5%:3%:2%. The mobile system was monitored at a flow of 0.60 ml/minute. Larotrectinib and internal standard (lenvatinib) were determined in the multiple reaction monitoring procedure with +ve electro-spray ionization with particular pair of mass to charge fraction. The findings of the matrix factor at low quality control (LQC) and high quality control (HQC) levels were less than 3.91 (% coefficient of variance). The average recovery value was 98.91% (95.34%–102.39%) for the analyte. Larotrectinib was stable in plasma spiked at LQC, median quality control, and HQC standards at room temperature (bench-top) for about 24 hours with a mean percentage above 95.92%. Freeze and thaw stability was evaluated after five cycles with a mean percentage above 96.98%. Long-term stability was evaluated for 24 days at −20°C and −70°C with mean percentage values between 95.37% and 98.45%. The outcomes of rabbit kinetics produced the Tmax and Cmax of 5.99 ± 0.09 and 42.87 ± 1.02 ng/ml, correspondingly. The AUC0→last and t1/2 outcomes were 314.75 ± 7.51 ng.hour/ml and 5.08 ± 0.14, individually. The established approach was successfully used to investigate the pharmacokinetics of larotrectinib in the biological matrices for future studies.
Key words: Larotrectinib, Tyrosine kinase, Bioanalytical method, Specificity, Accuracy.
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