Development and Validation of an LC-MS/MS Analytical Method for Quantitative Determination of Pazopanib in Plasma Using Erlotinib as an Internal Standard: Application in Pharmacokinetic Studies

Abstract

This study presents the development and validation of a robust LC-MS/MS analytical method for the quantitative determination of pazopanib in human plasma. Pazopanib, a tyrosine kinase inhibitor, was analyzed using erlotinib as an internal standard (IS) under optimized chromatographic and spectrometric conditions. The method employs a Zorbax SB-C18 column with a mobile phase comprising 0.2% formic acid in water (A) and methanol (B) at a flow rate of 0.4 mL/min. Plasma sample preparation involved protein precipitation using acetonitrile and subsequent centrifugation. The method validation adhered to ICH M10 and EMEA guidelines, assessing parameters such as specificity, linearity, accuracy, precision, and recovery.

The calibration curve exhibited linearity across the range of 62.5–32,000 ng/mL (R² > 0.999), with weight-based regression applied for accurate quantitation. Specificity tests confirmed minimal matrix interference for pazopanib and erlotinib, with acceptable signal-to-noise ratios. Intra- and inter-day precision (RSD%) values were below 6.8%, meeting the criteria for method precision. Recovery studies indicated consistent and reproducible extraction efficiency, with a mean recovery of 98.2% for pazopanib and 96.7% for the IS. The method demonstrated robust performance across three validation days, including the analysis of spiked plasma samples from healthy volunteers. Key pharmacokinetic parameters were derived following single-dose pazopanib administration, with plasma concentrations monitored at multiple time points over 72 hours.

The proposed LC-MS/MS method provides a reliable and reproducible analytical tool for pharmacokinetic studies of pazopanib, ensuring accurate plasma quantitation with high specificity and sensitivity. This validated method is suitable for clinical and bioequivalence studies requiring the quantification of pazopanib in complex biological matrices.