What question did this study set out to answer?

This research aims to develop an optimized UPLC-MS/MS method to quantify pazopanib and GSK-1268997 and evaluate their drug-drug interactions with nicardipine.

April 24, 2026Open Access

Optimized UPLC-MS/MS Method for the Simultaneous Quantification of Pazopanib and GSK-1268997 and Its Application to Drug-Drug Interaction Studies

Key Points

This research aims to develop an optimized UPLC-MS/MS method to quantify pazopanib and GSK-1268997 and evaluate their drug-drug interactions with nicardipine.
Developed a UPLC-MS/MS method for simultaneous quantification of pazopanib and GSK-1268997.
Conducted in vitro studies using rat and human liver microsomes to investigate metabolism.
Performed an in vivo pharmacokinetic study in rats to assess the impact of nicardipine on pazopanib metabolism.
Assay demonstrated linearity between 20–60,000 ng/mL for pazopanib and 10–30,000 ng/mL for GSK-1268997.
Co-administration of nicardipine increased pazopanib exposure significantly, with AUC rising by 4.03- to 4.31-fold.
Pazopanib's maximum plasma concentration increased by 1.60-fold, while plasma clearance decreased by 78.26%.

Abstract

Introduction: Pazopanib, an oral vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR-TKI), is approved for treating advanced renal cell carcinoma (RCC). However, pazopanib can cause hypertension, often necessitating co-administration with antihypertensives like nicardipine. Given their shared metabolic pathway via cytochrome P450 3A4 (CYP3A4), this study investigated their potential drug-drug interaction (DDI). Methods: An ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous quantification of pazopanib and its metabolite, GSK-1268997. This method was applied to in vitro inhibition studies using rat liver microsomes (RLM) and human liver microsomes (HLM), as well as to an in vivo pharmacokinetic study in rats, to evaluate the impact of nicardipine on pazopanib metabolism. Results: The assay was linear over the concentration ranges of 20– 60,000 ng/mL for pazopanib and 10– 30,000 ng/mL for GSK-1268997. The intra- and inter-day precision (relative standard deviations, RSD%) for the analytes ranged from 1.5% to 14.5%, with accuracy (relative errors, RE%) within ± 10.2%. The method also demonstrated acceptable selectivity, stability, matrix effect, and recovery. In vitro, nicardipine inhibited the metabolism of pazopanib in both RLM and HLM. In rats, co-administration of nicardipine significantly increased pazopanib exposure. The AUC (0–t) and AUC (0–∞) of pazopanib were increased by 4.03- and 4.31-fold, respectively, while the maximum plasma concentration (C max ) was increased by 1.60-fold. Conversely, the plasma clearance (CLz/F) was decreased by 78.26%. Discussion: The findings demonstrated that nicardipine significantly inhibited the metabolism of pazopanib both in vitro and in vivo, leading to substantially increased systemic exposure of pazopanib. This clinically significant finding suggests that, when these two drugs are used in combination, plasma drug concentrations should be closely monitored and the need for dose adjustment should be considered. Keywords: pazopanib, nicardipine, GSK-1268997, UPLC-MS/MS

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