Lipid Nanoparticle Encapsulated Chemotherapeutic Drugs Quantitation In vivo using Liquid Chromatography-coupled Electrospray Ionization Tandem Mass Spectrometry

Abstract JOURNAL/jpin/04.03/02275668-990000000-00067/figure1/v/2026-03-27T045519Z/r/image-tiff Systemic chemotherapeutic drugs such as paclitaxel (PAC) and lenvatinib (LEV) are widely utilized in the treatment of solid tumors. Although their pharmacological detection methods have been well documented, the growing interest in lipid-based nanoparticle (LNP) delivery systems necessitates the advancement of robust methods for in vivo quantification. In this study, we developed and validated a method of liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the quantification of PAC and LEV encapsulated in peptide-guided LNP (PGsLNP-PAC and PGsLNP-LEV). Initial method development was performed in vitro , followed by in vivo analysis using mice administered either the native drugs or the drugs encapsulated in nanoparticles. The quantification of PAC and LEV was within the linear ranges of 2–500 ng/mL and 0.08–20 ng/mL, with correlation coefficients ( R 2 ) of 0.9986 and 0.9998, respectively. The detection was performed using electrospray ionization positive ion mode and quantified by multiple reaction monitoring (MRM), which showed strong signal intensities for the parent ion ( m /z) transition pairs 876 → 308 and 427 → 370 for PAC and LEV, respectively. The stable-isotope-labeled internal standards 6α-OH-PAC-d5 and LEV-d4 were used with transition pairs 897 → 313 and 431 → 370 in MRM mode to correct the errors. The inter- and intra-day precision of low quality control (QC) to high QC for PAC and LEV ranged from 2.0%–18.1% to 0.9%–6.9%, respectively. The method was successfully applied by administering 200 nM of drugs for the quantification of PAC and LEV in tissue lysates. This ultra-sensitive approach enabled the accurate detection of trace-level concentrations of PAC (0.1810 mg ± 0.27/mL) and LEV (0.0066 mg ± 0.030/mL) in PGsLNP-PAC and PGsLNP-LEV. Furthermore, the method was validated by measuring the concentrations of native PAC in intravenously-administered C57BL/6 mice tissues. The reticular endothelial system, i.e. lung, spleen, and liver, showed a higher concentration of 396.1, 67.4, and 48.2 ng/g, respectively. We demonstrated a sensitive and robust LC-ESI-MS/MS method that can be suitable for pharmacokinetic evaluation and nanoparticle-based drug delivery assessment in cancer therapy.