Analysis of omeprazole and its main metabolites by liquid chromatography using hybrid micellar mobile phases

An amplified electrochemical sensor employing one-step synthesized nickel-copper-zinc ferrite/carboxymethyl cellulose/graphene oxide nanosheets composite for sensitive analysis of omeprazole

In this work, a signal amplification strategy was designed by the fabrication of a highly sensitive and selective electrochemical sensor based on nickel-copper-zinc ferrite (Ni0.4Cu0.2Zn0.4Fe2O4)/carboxymethyl cellulose (CMC)/graphene oxide nanosheets (GONs) composite modified glassy carbon electrode (GCE) for determination of omeprazole (OMP). The one-step synthesized Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction techniques. Then, the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE was applied to study the electrochemical behavior of the OMP. Electrochemical data show that the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE exhibits superior electrocatalytic performance on the oxidation of OMP compared with bare GCE, GONs/GCE, CMC/GONs/GCE and MFe2O4/GCE (M = Cu, Ni and Zn including single, double and triple of metals) which can be attributed to the synergistic effects of the nanocomposite components, outstanding electrical properties of Ni0.4Cu0.2Zn0.4Fe2O4 and high conductivity of CMC/GONs as well as the further electron transport action of the nanocomposite. Under optimal conditions, the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE offers a high performance toward the electrodetermination of OMP with the wide linear-range responses (0.24-5 and 5-75 μM), lower detection limit (0.22 ± 0.05 μM), high sensitivity (1.1543 μA μM-1 cm-2), long-term signal stability and reproducibility (RSD = 2.54%). It should be noted that the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE sensor could also be used for determination of OMP in drug and biological samples, indicating its feasibility for real analysis.

Simultaneous determination of omeprazole and their main metabolites in human urine samples by capillary electrophoresis using electrospray ionization-mass spectrometry detection

We report a novel method for the simultaneous determination of omeprazole and their main metabolites (omeprazole sulphide, omeprazole sulphone and 5-hydroxy omeprazole) in human urine samples. For this purpose, two new capillary electrophoresis (CE) methods were developed for the simultaneous determination of target compounds, using initially diode-array for optical detection and electrospray ionization-mass spectrometry (ESI-MS) for metabolites identification and identity confirmation. A new metabolite (5-hydroxysulphide omeprazole) was identified by electrospray ionization multi-stage mass spectrometry (ESI-MS2) fragment which was then used to support the proposed chemical structure. Pharmacokinetic results using CE method were compared with those obtained when a HPLC method was used. Equivalent pharmacokinetics profiles resulted when any analytical methods were carried out.

Relative bioavailability and pharmacokinetic comparison of two different enteric formulations of omeprazole

In order to comply with the requirements for a drug listed in China, the study was developed to compare the pharmacokinetics and relative bioavailability of two different enteric formulations of omeprazole (OPZ) in healthy Chinese subjects. A total of 32 volunteers participated in the study. Plasma concentrations were analyzed by nonstereospecific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method. After administration of a single 40-mg dose of the two OPZ formulations, the comparative bioavailability was assessed by calculating individual AUC(0‒t) (the area under the concentration-time curve from time zero to the last measurable concentration), AUC(0‒∞) (the area under the concentration-time curve extrapolated to infinity), C(max) (the maximum observed concentration), and T(peak) (the time to C(max)) values of OPZ, 5-hydroxyomeprazole (OH-OPZ), and omeprazole sulfone (OPZ-SFN), respectively. The 90% confidence intervals (CIs) of AUC(0‒t), AUC(0‒∞), and C(max) were 85.4%‒99.0%/88.8%‒98.6%/87.6%‒99.4%, 85.5%‒99.2%/89.0%‒98.6%/88.5%‒101.3%, and 72.3%‒87.6%/79.6%‒91.1%/88.4%‒99.1% for OPZ/OH-OPZ/OPZ-SFN, respectively, and T(peak) values did not differ significantly. In this study, the test formulation of OPZ in fasting healthy Chinese male volunteers met the Chinese bioequivalance standard to the reference formulation based on AUC, C(max), and T(peak).

Recent theoretical and practical applications of micellar liquid chromatography (MLC) in pharmaceutical and biomedical analysis

Micellar liquid chromatography (MLC) is an analytical technique belonging to the wide range of reversed-phase liquid chromatographic (RP-LC) separation techniques. MLC with the use of surfactant solutions above its critical micellar concentration (CMC) and the addition of organic modifiers is currently an important analytical tool with still growing theoretical considerations and practical applications in pharmaceutical analysis of drugs and other biologically active compounds. The use of MLC as an alternative, relatively much faster in comparison to conventional chromatographic separation techniques has several advantages, especially as being suitable for screening pharmaceutical analysis. The analytical data received from MLC analysis are considered a useful source of information to predict passive drug absorption, drug transport and other pharmacokinetics and physicochemical measures of pharmaceutical substances. In the review several MLC assays for determination of drugs and other active compounds in biological samples were compared and critically discussed. The presented overview provides information on recent applications and achievements connected with the practical use of MLC. The review covers fields of interest related to theory and mechanism of MLC separation, direct applications of MLC in pharmaceutical analysis, including optimization and efficiency of separation with the use of modification of stationary phase and mobile phase compositions as well as the determination of physicochemical characteristics of drugs by MLC.