Comparison of derivative spectrophotometric and liquid chromatographic methods for the determination of omeprazole in aqueous solutions during stability studies

Identification and structural characterization of the stress degradation products of omeprazole using Q-TOF-LC-ESI-MS/MS and NMR experiments: evaluation of the toxicity of the degradation products

Omeprazole (OMP), a prototype proton pump inhibitor used for the treatment of peptic ulcers and gastroesophageal reflux disease (GERD), was subjected to forced degradation studies as per ICH guidelines Q1A (R2).

Stability of Omeprazole Sodium and Pantoprazole Sodium Diluted for Intravenous Infusion

Background:

Proton-pump inhibitors are often administered by intravenous infusion to raise intragastric pH and prevent rebleeding following endoscopic treatment of bleeding ulcers. Currently, the manufacturers of omeprazole and pantoprazole injections recommend that infusions prepared by dilution in NaCl 0.9% should be used within 12 or 3 hours, respectively. Administration at the ward level would be facilitated if these drugs were known to be stable for up to 24 hours.

Objective:

To determine whether omeprazole and pantoprazole diluted for infusion in NaCl 0.9% or dextrose 5% are sufficiently stable to allow preparation of 24 hour infusion bags.

Methods:

Intravenous 500 mL bags of NaCl 0.9% or dextrose 5% containing 200 mg of either omeprazole or pantoprazole were prepared. While stored at 22 °C, samples were withdrawn at intervals up to 10 days, and pH and drug content were measured. ANOVA was used to compare drug concentrations at preparation with those after storage.

Results:

The pH of the infusions did not alter by more than 0.2 units over 48 hours, but decreased subsequently. The measured concentrations of both omeprazole and pantoprazole decreased during storage. The decrease in concentration was greater in dextrose 5% than in NaCl 0.9% and was related to storage time. However, for both drugs, the mean decrease did not exceed 6% over the first 48 hours.

Conclusions:

Infusions of omeprazole or pantoprazole can be maintained for up to 48 hours without significant loss of active drug content. Maintaining the same bag for 48 hours may provide cost savings compared with the present practice of replacing bags more frequently.

New sensitive kinetic spectrophotometric methods for determination of omeprazole in dosage forms

New rapid, sensitive, and accurate kinetic spectrophotometric methods were developed, for the first time, to determine omeprazole (OMZ) in its dosage forms. The methods were based on the formation of charge-transfer complexes with both iodine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The variables that affected the reactions were carefully studied and optimized. The formed complexes and the site of interaction were examined by UV/VIS, IR, and ¹H-NMR techniques, and computational molecular modeling. Under optimum conditions, the stoichiometry of the reactions between OMZ and the acceptors was found to be 1 : 1. The order of the reactions and the specific rate constants were determined. The thermodynamics of the complexes were computed and the mechanism of the reactions was postulated. The initial rate and fixed time methods were utilized for the determination of OMZ concentrations. The linear ranges for the proposed methods were 0.10–3.00 and 0.50–25.00 μg mL⁻¹ with the lowest LOD of 0.03 and 0.14 μg mL⁻¹ for iodine and DDQ, respectively. Analytical performance of the methods was statistically validated; RSD was <1.25% for the precision and <1.95% for the accuracy. The proposed methods were successfully applied to the analysis of OMZ in its dosage forms; the recovery was 98.91–100.32% ± 0.94–1.84, and was found to be comparable with that of reference method.

Simultaneous Estimation of Esomeprazole and Domperidone by UV Spectrophotometric Method

A novel, simple, sensitive and rapid spectrophotometric method has been developed for simultaneous estimation of esomeprazole and domperidone. The method involved solving simultaneous equations based on measurement of absorbance at two wavelengths, 301 nm and 284 nm, lambda max of esomeprazole and domperidone respectively. Beer's law was obeyed in the concentration range of 5-20 mug/ml and 8-30 mug/ml for esomeprazole and domperidone respectively. The method was found to be precise, accurate, and specific. The proposed method was successfully applied to estimation of esomeprazole and domperidone in combined solid dosage form.

Analytical methodologies for the determination of omeprazole: An overview

Omeprazole, a gastric acid pump inhibitor, dose-dependently controls gastric acid secretion; the drug has greater antisecretory activity than histamine H(2)-receptor antagonists. Omeprazole has been determined in formulations and biological fluids by a variety of methods such as spectrophotometry, high-performance liquid chromatography with ultraviolet detection and liquid chromatography coupled with tandem mass spectrometry. The overview includes the most relevant analytical methodologies used in its determination since the origin still today.

Degradation of lansoprazole and omeprazole in the aquatic environment

Lansoprazole and omeprazole degrade in water leading to sulfides, benzimidazolones and a red complex material. Degradation is accelerated in acid medium and by solar simulator irradiation. Benzimidazoles, dianilines and pyridines have also been identified.

Recent Developments of Derivative Spectrophotometry and Their Analytical Applications

Articles about the development of derivative spectrophotometric methods and analytical applications of derivative spectrophotometry (DS) published in the last nine years (since 1994) are reviewed.

Development of an intravenously injectable chemically stable aqueous omeprazole formulation using nanosuspension technology

Omeprazole is a proton pump inhibitor, which is used for the treatment of peptic ulcers, reflux esophagitis and Zollinger-Ellison syndrome. It is a poorly soluble, chemically labile drug with a high degradation rate in aqueous media. The aim of this study was to show the feasibility of omeprazole stabilization using the DissoCubes technology and to find optimal production parameters for a stable, highly concentrated omeprazole nanosuspension. The high performance liquid chromatography analysis has proved the predominance of the nanosuspension produced by high pressure homogenization in comparison to an aqueous solution. Even 1 month after production no discoloration or drug loss was recognizable when the nanosuspension was produced at 0 degree C. As a result it can be stated that the production of nanosuspensions by high pressure homogenization is suitable for preventing degradation of labile drugs.

Validation of the spectrophotometric determination of omeprazole and pantoprazole sodium via their metal chelates

Spectrophotometric procedures for the determination of two irriversible proton pump inhibitors, omeprazole (OMZ) and pantoprazole (PNZ) sodium have been developed, the procedures are based on the formation of 2:1 chelates of both drugs with different metal ions. Pantoprazole sodium is quantified by a stability-indicating procedure through chelation with iron (III) in aqueous-ethanol medium to form an orange chelate picked at 455 nm. The procedure retains its accuracy in presence of up to 70% of its degradate, sulfenic acid prepared by degrading the pure drug in borate buffer of pH 8 at 37 degrees C for 5 days. The colored chelates of OMZ in ethanol are determined spectrophotometrically at 411, 339 and 523 nm using iron (III), chromium (III) and cobalt (II), respectively. Regression analysis of Beer's plots showed good correlation in the concentration range of 15-95, 10-60 and 15-150 microml(-1) of pure OMZ using iron (III), chromium (III) and cobalt (II), respectively, and in the range of 30-300 microg ml(-1) of PNZ sodium using iron (III). The limits of detection are 0.22-3.65 microml(-1) while limits of quantitation range between 0.74 and 12.17 microg ml(-1). The optimum assay conditions are investigated and the recovery of the cited drugs from their dosage forms ranges from 97.2 to 100.3%. Good values of precision are obtained, intraday R.S.D. are 0.93-1.75% and the inter day R.S.D. are 0.51-3.29%.

First-order UV-derivative spectrophotometry in the analysis of omeprazole and pantoprazole sodium salt and corresponding impurities

The first-order UV-derivative spectrophotometry, applying zero-crossing method was developed for the determination of omeprazole (OM), omeprazole sulphone (OMS), pantoprazole sodium salt (PANa), and N-methylpantoprazole (NPA) in methanol-ammonia 4.0% v/v, where the sufficient spectra resolutions of drug and corresponding impurity were obtained, using the amplitudes 1D(304), 1D(307), 1D(291.5) and 1D(296.5), respectively. Method showed good linearity in the ranges (microg ml(-1)): 1.61-17.2 for OM; 2.15-21.50 for OMS; 2.13-21.30 for PANa and 2.0-20.0 for NPA, accuracy and precision (repeatability and reproducibility). The experimentally determined values of LOD (microg ml(-1)) were 1.126; 0.76; 0.691 and 0.716 for OM, OMS, PANa and NPA, respectively. The obtained values of 2.91% w/w for OMS and 3.58% w/w for NPA in the presence of their parent drug, by applying the method of standard additions, point out the usage of the proposed method in stability studies. Zero-crossing method in the first-order derivative spectrophotometry showed the impurity-drug intermolecular interactions, due to the possible intermolecular hydrogen bonds, confirmed by divergences of experimentally obtained amplitudes for impurities OMS and NPA in comparison to expected values according to regression equations of calibration graphs.

Spectrophotometric determination of omeprazole, lansoprazole and pantoprazole in pharmaceutical formulations

The compensation method and other chemometric methods (derivative, orthogonal function and difference spectrophotometry) have been applied to the direct determination of omeprazole, lansoprazole and pantoprazole in their pharmaceutical preparations. The methods have been validated; the limits of detection were found to be 3.3x10(-2), 3.0x10(-2) and 3.5x10(-2) microgram ml(-1) for the three drugs, respectively. The repeatabililty of the methods were found to be 0.3-0.5%. The linearity ranges were found to be 0.5-3.5 microgram ml(-1). The proposed methods have been applied to the determination of the three drugs in their grastro-resistant formulations. The difference spectrophotometric (DeltaA) method is unaffected by the presence of acid induced degradation products; hence can be used as a stability indicating assay.

First-derivative spectrophotometric and LC determination of nifedipine in Brij 96 based oil/water/oil multiple microemulsions on stability studies

A first-derivative spectrophotometric (1D(387)) method was developed for the determination of nifedipine in oil/water/oil (O/W/O) multiple microemulsions during stability studies. The UV first-derivative spectra were recorded over the wavelength range 200-600 nm (Delta lambda=16). The derivative procedure was based on the linear relationship between nifedipine concentration and the first-derivative amplitude at 387 nm. This method was validated and compared with a liquid chromatography (LC) procedure used for the quantitative analysis of the drug. Both methods showed excellent precision and accuracy with values of 2.09 and 1.82%, respectively, for the LC method and of 1.53 and 1.64%, respectively, for the 1D(387) method. The established linearity range was 5-30 microg ml(-1) with r(2) values of 0.9980 and 0.9988 for LC and first-derivative procedures, respectively. Nifedipine recoveries from spiked placebos were >95% for both methods over the linear range analysed. These methods have been successfully used for determining of nifedipine content of multiple microemulsions during stability studies, since there was no interference with its decomposition products.