Development and Validation of an LC-MS/MS Method for Quantification of Osimertinib in Human Plasma: Application to Pharmacokinetic Studies

Abstract

A highly sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of osimertinib in human plasma, utilizing propranolol as an internal standard. Sample preparation involved protein precipitation with acetonitrile, followed by chromatographic separation on an Agilent Zorbax SB-C18 column. The mobile phase consisted of 0.2% formic acid in water (A) and acetonitrile (B), delivered at a flow rate of 0.4 mL/min. Detection was performed on a Quattro Micro quadrupole mass spectrometer equipped with an electrospray ionization source operating in positive ion mode. The method exhibited a linear dynamic range of 1.25 to 300 ng/mL for osimertinib, with a lower limit of quantification of 1.25 ng/mL. Intra- and inter-day precision and accuracy were within acceptable limits, with relative standard deviations not exceeding 10%. The method demonstrated excellent specificity, with no significant interference observed from endogenous plasma components. The validated method was successfully applied to a pharmacokinetic study involving healthy volunteers administered osimertinib, providing reliable and reproducible plasma concentration data over a 96-hour sampling period. This LC-MS/MS method offers a robust analytical tool for therapeutic drug monitoring and pharmacokinetic evaluations of osimertinib in clinical settings.