Highly sensitive method for the determination of omeprazole in human plasma by liquid chromatography–electrospray ionization tandem mass spectrometry: application to a clinical pharmacokinetic study

Abstract

A highly sensitive, rapid assay method has been developed and validated for the estimation of omeprazole (OPZ) in human plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive-ion mode. The assay procedure involves alkalinization of plasma followed by simple liquid-liquid extraction of OPZ and lansoprazole (internal standard, IS) from human plasma with acetonitrile. Chromatographic separation was achieved with 0.01 M ammonium acetate:acetonitrile (40:60, v/v) at a flow rate of 0.25 mL/min on an Inertsil ODS 3 column with a total run time 2.5 min. The MS/MS ion transitions monitored were 346.1 --> 198.1 for OPZ and 370.1 --> 252.1 for IS. Method validation and clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.05 ng/mL and the linearity was observed from 0.05 to 10.0 ng/mL. The intra-day and inter-day precisions were in the ranges 2.09-8.56 and 5.29-8.19%, respectively. This novel method has been applied to a pharmacokinetic study of OPZ in humans.

Improvement and Validation of a High-Performance Liquid Chromatography in Tandem Mass Spectrometry Method for Monitoring of Omeprazole in Plasma

“…"One of the advantages was the use of isotope-labeled IS and a more selective sample preparation procedure such as SPE, which helps to eliminate the matrix effect and improves assay selectivity 28 , as in the present study". The authors' approach achieved good recoveries, with average values of 86% to 104%, which are similar to those reported by Dodgen and coworkers 20 and Macek and coworkers 22 or better than those reported elsewhere (>63% 23 , 71% to 74% 24 , and 83% to 87% 17 ). These recoveries were achieved thanks to an ultraclean polymeric sorbent of SPE, which has bimodal porosity and a high surface area.…”

“…The LC-MS/MS the authors used had an LLOQ of 1.5 ng/mL for OME and higher sensitivity and selectivity than authors who used HPLC with UV detection between 3-96 ng/mL [13][14][15][16][17][18][19] . The most relevant LC-MS/MS-based methods have sensitivities of 0.05 ng/mL 23,24 , 0.4 ng/mL 21 , and 1.2 ng/mL 22 , which were slightly lower than those used by the authors of the present study. In all of these studies, the run times were longer, and samples were prepared using LLE or PPT.…”

“…Our chromatographic run lasted 1.2 min, which is shorter than times recorded elsewhere (>1.3 min 13,15,17,[21][22][23][24] or even >16 min 17 ). The authors used a Zorbax Extend C-18 high-resolution column, which enabled us to work with a high flow of 0.8 mL min and provided a short analysis time.…”

“…The method used only 200 L of plasma, which is less than that reported elsewhere (250 to 450 L [21][22][23][24] or even 1000 L 17 ). Hence, the quantity of plasma required to validate the bioanalytical methods is reduced.…”

“…These results are in line with those of previous reports on the pharmacokinetics of OME by Liu and coworkers (C max of 1330.46 ± 758.07 ng/mL) 38 . Other authors reported lower C max owing to lower doses of OME 24,39 . The high inter-subject variability indicated by the error bars in Fig 2 is similar to the findings reported by other authors 22,38 , thus making them suitable for monitoring.…”