Determination of omeprazole in pharmaceuticals by derivative spectroscopy

Development and Validation of a Novel Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Related Substances of Ketoprofen and Omeprazole in Combined Capsule Dosage Form

A novel, simple, sensitive, selective and reproducible stability-indicating high performance liquid chromatographic method was developed for the quantitative determination of degradation products and process-related impurities of ketoprofen (KET) and omeprazole (OMZ) in combined oral solid dosage form. Chromatographic separation was achieved on a Phenomenex Luna C18 (2) column (150 × 4.6 mm, 5 μm) under gradient elution by using a binary mixture of potassium dihydrogen phosphate buffer and acetonitrile at a flow rate of 0.8 mL/min. Chromatogram was monitored at 233 nm for KET impurities and at 305 nm for OMZ impurities using a dual wavelength UV detector. Resolution for KET and OMZ and 14 impurities was found to be >1.5 for any pair of components. Typical retention behaviors of impurities at various pH values were depicted graphically. To prove the stability-indicating power of the method, the drug product was subjected to hydrolytic, oxidative, photolytic, humidity and thermal stress conditions as per ICH. The developed method was validated according to the current ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness and robustness.

Spectrophotometric determination of peptic ulcer sulfur-containing drugs in bulk form and in tablets

Two spectrophotometric procedures are suggested for the determination of three irreversible proton pump inhibitors, rabeprazole (RAB), omeprazole (OMP) and pantoprazole (PAN) in pure form and in different pharmaceutical formulations. The first method is based on the oxidation of RAB and PAN with potassium iodate in an acidic medium followed by extracting the liberated iodine with cyclohexane and measurement at λ = 520 nm. Beer's law is valid in the concentration ranges from 10-400 and 5-400 µg ml(-1) for RAB and PAN, respectively. The apparent molar absorptivities of the resulting coloured product were found to be 1.34 × 10(3) and 1.64 × 10(3) l.mol(-1). cm(-1) for RAB and PAN, respectively. The second method is based on the interaction of the basic drugs, OMP, RAB and PAN, in 1,2-dichloroethane with bromophenol blue (BPB), bromocresol green (BCG) and bromocresol purple (BCP) in the same solvent to produce stable coloured ion pairs with maximum absorbance at 385-405 nm. Regression analysis of Beer's plots showed good correlation in the concentration ranges 10-60, 10-60 and 5-40 µg ml(-1) for OMP, 10-150, 10-150 and 10-60 µg ml(-1) for RAB and 10-250, 10-150 and 10-100 µg ml(-1) for PAN with BPB, BCG and BCP reagents, respectively. The limits of detection are 0.46-7.69 µg ml(-1) and limits of quantitation range between 1.52-8.53 µg ml(-1). The optimum assay conditions were investigated and the recovery of the drugs from their dosage forms ranged from 99.33% to 100.5%. Intraday relative standard deviations (RSD) were 0.029-1.397% and the correlation coefficients ranged from 0.9992 to 1. The two methods can be applied successfully for the determination of these drugs in tablets. The results of analysis were validated statistically through recovery studies.

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.

Characterization of a derivative photoacoustic spectrometer

A design of derivative photoacoustic spectrometer is presented in this article. It mainly includes a wavelength-intensity splitter and a complementary chopper. In our design, a dual wavelength derivative method is introduced to implement a derivative operation. Through the wavelength-intensity splitter, two beams are obtained and then complementarily modulated by the complementary chopper to satisfy the first derivative requirements as well as to achieve the differential of photoacoustic signals. As examples, the first derivative photoacoustic spectra of He-Ne laser and xenon lamp are also presented in this article. The results show that the first derivative photoacoustic spectrum can provide a superior fine spectral structure and spectral resolution compared to the photoacoustic absorption spectrum.

Reversed-Phase High Performance Liquid Chromatographic Method for the Determination of Lansoprazole, Omeprazole and Pantoprazole Sodium Sesquihydrate in Presence of Their Acid-Induced Degradation Products

A simple sensitive, selective and accurate reversed-phase high performance liquid chromatographic method was developed and validated for the quantitative determination of lansoprazole, omeprazole and pantoprazole sodium sesquishydrate in the presence of their acid-induced degradation products. The three compounds were monitored at 280 nm using Nova-Pak C(18) column and a mobile phase consisting of 0.05 M potassium dihydrogen phosphate : methanol : acetonitrile (5 : 3 : 2 v/v/v). Linearity ranges were 2-20 microg ml(-1), 2-36 microg ml(-1) and 0.5-20 microg ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The corresponding recoveries were 100.61+/-0.84%, 100.50+/-0.80% and 99.78+/-0.88%. The minimum detection limits were 0.55, 0.54 and 0.03 microg ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The method could be successfully applied to the determination of pure, laboratory prepared mixtures and pharmaceutical dosage forms. The results obtained were compared with the reported methods for lansoprazole and pantoprazole or the official U.S.P method for omeprazole.

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.

Anodic voltammetric assay of lansoprazole and omeprazole on a carbon paste electrode

The electrochemical oxidations of lansoprazole and omeprazole have been studied at a carbon paste electrode by cyclic and differential-pulse voltammetry in Britton-Robinson buffer solutions (0.04 M; pH 6.0-10.0). The drug produced a single oxidation step. By differential-pulse voltammetry, a linear response was obtained in B-R buffer pH 6.0 in a concentration range from 2.0 x 10(-7) to 5.0 x 10(-5) M for lansoprazole or omeprazole. The detection limits were 1.0 x 10(-8) and 2.5 x 10(-8) M for lansoprazole and omeprazole, respectively. The method was successfully applied for the analysis of omeprazole and lansoprazole in capsules. The results were comparable to those obtained by spectrophotometry.

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.

Simultaneous determination of valsartan and hydrochlorothiazide in tablets by first-derivative ultraviolet spectrophotometry and LC

First-derivative ultraviolet spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine valsartan and hydrochlorothiazide simultaneously in combined pharmaceutical dosage forms. The derivative procedure was based on the linear relationship between the drug concentration and the first derivative amplitudes at 270.6 and 335 nm for valsartan and hydrochlorothiazide, respectively. The calibration graphs were linear in the range of 12.0-36.1 microg x ml(-1) for valsartan and 4.0-12.1 microg x ml(-1) for hydrochlorothiazide. Furthermore, a high- performance liquid chromatographic procedure with ultraviolet detection at 225 nm was developed for a comparison method. For the HPLC procedure, a reversed phase column with a mobile phase of 0.02 M phosphate buffer (pH 3.2)-acetonitrile (55: 45; v/v), was used to separate for valsartan and hydrochlorothiazide. The plot of peak area ratio of each drug to the internal standard versus the respective concentrations of valsartan and hydrochlorothiazide were found to be linear in the range of 0.06-1.8 and 0.07-0.5 microg x ml(-1), respectively. The proposed methods were successfully applied to the determination of these drugs in laboratory-prepared mixtures and commercial tablets.

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

A first derivative spectrophotometric method was developed for the determination of omeprazole in aqueous solutions during stability studies. The derivative procedure was based on the linear relationship between the omeprazole concentration and the first derivative amplitude at 313 nm. The first derivative spectra was developed between 200 and 400 nm (deltalambda = 8). This method was validated and compared with the official high-performance liquid chromatography (HPLC) method of the USP. It showed good linearity in the range of concentrations studied (10-30 microg ml(-1)), precision (repeatability and inter-day reproducibility), recovery and specificity in stability studies. It also seemed to be 2.59 times more sensitive than the HPLC method. These results allowed to consider this procedure as useful for the rapid analysis of omeprazole in stability studies since there was no interference with its decomposition products.

Determination of Lansoprazole in pharmaceutical dosage forms by two different spectroscopic methods

Two different ultraviolet (UV) spectroscopic methods were developed for determination of Lansoprazole in pharmaceutical dosage forms. The solutions of the standard and the sample were prepared in 0.1 M NaOH and phosphate buffer pH 6.6. Both UV spectrophotometric and derivative spectroscopic techniques were applied. Second-order derivative spectra were generated between 200 and 400 nm at N = 9, deltalambda = 31.5. The linear range for the UV spectrophotometric method was 3.0-25.0 microg ml(-1) and that for the derivative spectroscopic method was 0.5-25.0 microg ml(-1). The developed methods were applied to three different pharmaceutical preparations. The percentage recovery was 100.2%.