M. Abdelkawy

Simultaneous HPTLC and RP‐HPLC methods for determination of bumadizone in the presence of its alkaline‐induced degradation product

Accurate, selective, sensitive and precise HPTLC-densitometric and RP-HPLC methods were developed and validated for determination of bumadizone calcium semi-hydrate in the presence of its alkaline-induced degradation product and in pharmaceutical formulation. Method A uses HPTLC-densitometry, depending on separation and quantitation of bumadizone and its alkaline-induced degradation product on TLC silica gel 60 F(254) plates, using hexane-ethyl acetate-glacial acetic acid (8:2:0.2, v/v/v) as a mobile phase followed by densitometric measurement of the bands at 240 nm. Method B comprises RP-HPLC separation of bumadizone and its alkaline-induced degradation product using a mobile phase consisting of methanol-water-acetonitrile (20:30:50, v/v/v) on a Phenomenex C(18) column at a flow-rate of 2 mL/min and UV detection at 235 nm. The proposed methods were successfully applied to the analysis of bumadizone either in bulk powder or in pharmaceutical formulation without interference from other dosage form additives, and the results were statistically compared with the established method.

Novel spectrophotometric determination of flumethasone pivalate and clioquinol in their binary mixture and pharmaceutical formulation.

This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 μg/mL for FP, and 2-25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Validated Stability Indicating TLC-Densitometric Method for the Determination of Diacerein

This work presents an accurate, sensitive and selective thin-layer chromatography-densitometry method for the simultaneous determination of diacerein in the presence of rhein, the active metabolite and hydrolytic degradation product of diacerein, and emodin, the diacerein impurity, in bulk powder and different pharmaceutical formulations. Chromatographic separation was performed on aluminum plates precoated with 60 F254 silica gel using hexane-ethyl acetate-acetic acid (60:40:0.8, by volume) as a developing system and with detection at 230 nm. The retention factor values of diacerein, rhein and emodin were 0.12, 0.44 and 0.6, respectively. The method was successfully applied for the determination of these compounds with high sensitivity; the linearity ranges were found to be 0.5-10 µg/band (for diacerein and rhein) and 0.5-7 µg/band (for emodin). The developed method was validated according to International Conference on Harmonization guidelines and was applied for the determination of diacerein in different pharmaceutical formulations. Moreover, a statistical comparison between the results of the developed method and those of the reported reversed-phase high-performance liquid chromatography method showed no significant differences. This method can be used for the routine analysis of diacerein, rhein and emodin in quality control laboratories.

Kinetic study and mechanism of Niclosamide degradation

A spectrophotometric kinetic study of Niclosamide alkaline degradation as a function of drug concentration, alkaline concentration and temperature has been established utilizing double divisor-ratio spectra spectrophotometric method. The developed method allowed determination of Niclosamide in presence of its alkaline degradation products; namely; 2-chloro-4-nitro aniline (DEG I) and 5-chloro salicylic acid (DEG II) with characterization of its degradation mechanism. It was found that degradation kinetic of Niclosamide followed pseudo-first order under the established experimental conditions with a degradation rate constant (k) of 0.0829 mol/h and half life (t1/2) of 8.35 h. The overall degradation rate constant as a function of the temperature under the given conditions obeyed Arrhenius equation where the activation energy was calculated to be 3.41 kcal/mol.

Validated Chromatographic Methods for Simultaneous Determination of Amlodipine Besylate and Perindopril Arginine in Binary Mixtures and in Pharmaceutical Dosage Form

Two accurate, selective and precise chromatographic methods, namely TLC-densitometric method & RP-HPLC method & were developed and validated for the simultaneous determination of Amlodipine besylate and Perindopril Arginine in their binary mixtures. The developed TLC-densitometric method depends on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Chloroform:methanol:deionized water:glacial acetic acid:triethylamine (10:7:5:0.3:0.2, by volume) was used as developing system and the separated bands were scanned at 208 nm. Linear relationship was obtained in the range 1-10 μg for both drugs. The developed RP-HPLC depends on quantitative chromatographic separation of the studied drugs on a C18 column using phosphate Buffer:acetonitrile (60:40, v/v), pH=4.6 as a mobile phase delivered at constant flow rate of 1 mL.min-1 with UV detection at 210 nm. Calibration curves for Amlodipine besylate and Perindopril Arginine were constructed over the concentration range of 1-50 μg.mL-1 for both drugs. The proposed methods were successfully applied for determination of the studied drugs in their bulk powder and in pharmaceutical formulations. The proposed methods were statistically compared to each other using student’s t test and F-test and no significant difference was found between them.

SIMULTANEOUS DETERMINATION OF METHOCARBAMOL AND ITS RELATED SUBSTANCE (GUAIFENESIN) IN TWO TERNARY MIXTURES WITH IBUPROFEN AND DICLOFENAC POTASSIUM BY RP-HPLC METHOD

Accurate, sensitive, and precise RP-HPLC methods were developed and validated for determination of Methocarbamol and its related substance (Guaifenesin) in two ternary mixtures with Ibuprofen and Diclofenac potassium. The first mixture containing Methocarbamol, Ibuprofen, and Guaifenesin was separated using Isocratic elution on a Phenomenex C18 column using 0.05 M KH2PO4 (pH = 7): acetonitrile methanol (90:25:15, by volume) as a mobile phase at a flow rate of 1.2 mL.min−1 and UV detection at 220 nm. The second mixture containing Methocarbamol, Diclofenac potassium, and Guaifenesin was separated using Isocratic elution on a Phenomenex C18 column using 0.05 M KH2PO4 (pH = 7): acetonitrile (80:30, v/v) as a mobile phase at a flow rate of 1.5 mL.min−1 and UV detection at 278 nm. The proposed methods were successfully applied for determination of Methocarbamol, Ibuprofen, and Diclofenac potassium in presence of Methocarbamol related substance (Guaifenesin) either in bulk powder or in its pharmaceutical formulation.

Simultaneous Determination of Paracetamol and Diphenhydramine Hydrochloride in Presence of Paracetamol Degradation Product

Three sensitive , selective and precise stability indicating methods for simultaneous determination of Paracetamol and Diphenhydramine hydrochloride in their binary mixture and in presence of P-aminophenol; the potential impurity and degradation product of Paracetamol; were developed. In Method A, Paracetamol was determined in presence of Diphenhydramine Hydrochloride and P-aminophenol using the first derivative (1D) spectrophotometric method by measuring the peak amplitude at 264.5 nm where linear relationship was obtained in the range of 2-12 ?g mL-1 while Diphenhydramine Hydrochloride was determined in presence of Paracetamol and P-aminophenol using the first derivative of ratio spectra (1DD) method at 224 nm. Method B utilized chemometric techniques [Principal Component Regression (PCR) and Partial Least Squares(PLS)] which successfully applied to quantify both drugs and degradation product using the information included in the absorption spectra of appropriate solutions of the three compounds in the range of 220-340nm. Method C used HPTLC-densitometric method in which the aforementioned components were separated on silica gel plates using chloroform-ethyl acetate-ammonia solution (4:6:0.2, by volume) as a developing system. This was followed by quantitative densitometric measurement at 220 nm .Linear relationship were obtained in the concentration ranges of 0.4-1.6 ?g/band , 3-12 ?g /band and 0.4-1.6 ?g/band for Paracetamol, Diphenhydramine Hydrochloride and P-aminophenol respectively. The proposed methods have been successfully applied to the analysis of Paracetamol and Diphenhydramine Hydrochloride in their pharmaceutical formulation without interference from other dosage form additives and the results were statistically compared with official method.

Validated RP-HPLC and TLC-Densitometric Methods for Analysis of Ternary Mixture of Cetylpyridinium Chloride, Chlorocresol and Lidocaine in Oral Antiseptic Formulation.

This work was concerned with development, optimization, application and validation of reversed phase high performance liquid chromatography (RP-HPLC) and thin layer chromatography (TLC)-densitometric methods for analysis of cetylpyridinium chloride, chlorocresol and lidocaine in Canyon(®) gel. The first developed RP-HPLC method depended on chromatographic separation on a ZORBAX Eclipse Plus C8 column, with elution with a mobile phase consisting of 0.05% phosphoric acid solution : acetonitrile : methanol (15 : 24 : 61, by volume), pumping the mobile phase at a flow rate of 1.00 mL min(-1), with ultraviolet detection at 220 nm. While in the subsequently developed method, the TLC-densitometric method, complete separation of the studied mixture was achieved using methanol : acetone : acetic acid (7 : 3 : 0.2, by volume) as a mobile phase, aluminum plates precoated with silica gel 60 F254 as a stationary phase and 215 nm as the scanning wavelength. Factors affecting the developed methods were studied and optimized; moreover, methods had been validated as per the International Conference of Harmonization guideline and the results indicated that the suggested methods were reproducible, reliable and applicable for rapid routine analysis. Statistical comparison of the two developed methods with the reported HPLC ones using F- and Students t tests showed no significant difference.

Validated Chromatographic Methods for Simultaneous Determination of Tolfenamic Acid and Its Major Impurities

Two accurate, selective and precise chromatographic methods, namely thin-layer chromatography (TLC)-densitometric method and reversed phase high-performance liquid chromatography (RP-HPLC) method, were developed and validated for the simultaneous determination of tolfenamic acid (TOL) and its two major impurities, 2-chlorobenzoic acid (CBA) and 3-chloro-2-methylaniline (CMA), which are also reported to be its related substances. The developed TLC-densitometric method depended on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Hexane:chloroform:acetone:acetic acid (75:25:20:0.1, v/v/v/v) was used as a developing system and the separated bands were UV-scanned at 240 nm. Linear relationships were obtained in the range of 10-100 µg band(-1) for the drug and in the range of 0.1-1 µg band(-1) for the studied impurities. The developed RP-HPLC depended on chromatographic separation of the studied drugs on a C18 column using 0.05 M KH2PO4 buffer (pH 3):acetonitrile (45:55, v/v) as a mobile phase delivered at constant flow rate of 1 mL min(-1) with UV detection at 230 nm. Calibration curves for TOL and the two impurities were constructed over the concentration ranges of 10-100 µg mL(-1) for TOL and 0.01-0.1 µg mL(-1) for both CBA and CMA. Factors affecting the developed methods have been studied and optimized. Further, methods validation has been carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for determination of the studied drug in its bulk powder and in pharmaceutical formulation. The methods showed no significant difference when compared with the reported RP-HPLC one. The developed methods have advantages of being more sensitive and specific than the published methods.

Quantitative Determination of Synthesized Genotoxic Impurities in Nifuroxazide Capsules by Validated Chromatographic Methods

Two accurate, selective, and precise chromatographic methods, namely TLC-densitometric and reversed-phase (RP)-HPLC, were developed and validated for the simultaneous determination of nifuroxazide (NIF) and its four synthesized impurities, which are also reported to be its related substances in the range of 10-100 μg/band and 10-100 μg/mL for NIF in the TLC and RP-HPLC methods, respectively. The developed TLC-densitometric method depended on the separation and quantitation of the studied components on silica gel 60 F254 TLC plates. Ethyl acetate-acetone-methanol-ammonia (85 + 25 + 5 + 0.5, v/v/v/v) was used as the developing system, and the separated bands were UV-scanned at 230 nm. On the other hand, the developed RP-HPLC method depended on chromatographic separation using a C8 column at 25°C and an aqueous solution of 0.1% sodium lauryl sulfate-acetonitrile as the mobile phase delivered according to the gradient elution program. Factors affecting the developed methods were studied and optimized. Also, method validation was carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drug in its bulk powder and in its pharmaceutical formulation. The developed methods showed no significant difference when compared with the reported RP-HPLC one. Their advantage is being the first stability-indicating methods for NIF and its genotoxic impurities.