Essam F. Khamis

Quantitative determination of some thiazole cephalosporins through complexation with palladium (II) chloride

A simple and sensitive spectrophotometric method has been developed for the determination of five cephalosporins namely cefpodoxime (CFPD), ceftizoxime (CTIZ), ceftazidime (CZD), ceftriaxone (CTRX), and cefixime (CXIM). This method is based on the formation of yellow to yellowish brown complex between palladium (II) chloride and the investigated cephalosporins in the presence of sodium lauryl sulphate (SLS) as surfactant. The reaction conditions were studied and optimized. The procedure was validated. For each drug, the composition of this complex as well as its stability constant were also investigated. The proposed method was used for the determination of the above-mentioned drugs in their commercial preparations. The results were compared statistically with either official or published methods and showed no significant difference between the two methods.

Use of Cerium (IV) in the Spectrophotometric and Spectrofluorimetric Determinations of Penicillins and Cephalosporins in Their Pharmaceutical Preparations

Abstract Spectrophotometric and spectrofluorimetric procedures for the quantitative determination of four penicillins [Amoxycillin (AMX), Bacampicillin (BAC), Piperacillin (PPN) and Sultamcillin (SULT)] and ten cephalosporins [Cefadroxil (CDL), Cefamandole nafate (MAN), Cefuroxime axetil or sodium (CFX), Cefaclor (CFCR), Ceftazidime (CZD), Ceftizoxime (CTIZ), Ceftriaxone (CTRX), Cefoperazone (CPZ), Cefixime (CXIM) and Cefpodoxime proxetil (CFPD)] are described. Both methods are based on the acidic oxidation of the antibiotics with cerium (IV) at elevated temperature. The effect of the reagent concentration, volume of the acid,and the heating temperature were studied to optimize the reaction conditions. Each antibiotic was determined by either measuring the absorbance difference at 317 nm or the cerous inherent fluorescence at 256 and 356 nm for excitation and emission wavelengths, respectively. The two procedures have been successfully applied to the assay of these antibiotics in their pharmaceutical dosage forms. The obtained results have been statistically compared with those obtained by the official methods.

Selective spectrofluorimetric determination of phenolic β-lactam antibiotics through the formation of their coumarin derivatives

A simple, sensitive and selective spectrofluorimetric procedure was developed for the determination of amoxycillin, cefadroxil and cefoperazone. The method is based on the reaction between these drugs and ethyl acetoacetate, in acidic medium, to give yellow fluorescent products with excitation wavelengths ranging from 401 to 467 nm and emission wavelengths ranging from 465 to 503 nm. The reaction conditions were studied and optimized. The reaction obeyed Beers law over the range of 10.0-20.0, 1.5-1.0 and 50.0-100.0 microg ml(-1) for amoxycillin, cefadroxil and cefoperazone, respectively. Interferences from other antibiotics, drugs and dosage forms additives, in capsules and vials dosage forms, were investigated. The proposed method was applied to the analysis of pharmaceutical formulations (capsules and vials) containing the above antibiotics, either alone or in combination with other antibiotics or drugs. The validity of the method was tested by the recovery studies of standard addition which were found to be satisfactory. The results of the proposed method demonstrated that the method is equally accurate, precise and reproducible as the official methods (USP XXIII) and those published for the non-official binary mixtures.

Application of H-point standard additions method to spectrophotometric and spectrofluorimetric determinations of glafenine and glafenic acid in mixtures

H-point standard additions method (HPSAM), based on spectrophotometric and spectrofluorimetric measurements, was proposed for simultaneous determination of glafenine (G) and glafenic acid (GA). A study of the absorption spectra of G and GA in various pH media has been carried out. Reasonably resolved UV-absorption spectra were obtained with a solution adjusted at pH 4.5 with citric acid-phosphate buffer. Additionally, the fluorescence properties in aqueous micellar systems of anionic, cationic and non-ionic surfactants were investigated. Well resolved fluorescence spectra were established in aqueous Triton X-100 solution at pH 7.8 (citric acid-phosphate buffer). As a comparative method, UV-derivative spectrophotometry (based on zero-crossing technique) was suggested. First-derivative value at 352 nm ((1)D(352)) and second-derivative value at 366 nm ((2)D(366)) were selected for the quantification of G and GA, respectively. The relative standard deviations of the proposed methods approximate 2%. The proposed methods were evaluated through the analysis of commercial tablets. The results were accurate and precise.

Development of a differential pulse voltammetric method for the determination of Silymarin/Vitamin E acetate mixture in pharmaceuticals

Differential pulse voltammetric method was developed for determination of Silymarin (SMR)/Vitamin E acetate (VEA) mixture in pharmaceuticals. SMR and VE gave well-resolved diffusion-controlled anodic peaks at +756 and +444mV, respectively (versus Ag/AgCl) in Britton-Robinson buffer at pH 2.8. The solution conditions and instrumental parameters were optimized for their quantitative determination. The linear response was obtained in the range 0.1-4.0mgL(-1) with a detection limit of 0.03mgL(-1) for SMR and 0.05-4.0mgL(-1) with a detection limit of 0.01mgL(-1)for VEA.

Development and Validation of a High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Two Binary Mixtures Containing Ketorolac Tromethamine with Phenylephrine Hydrochloride and with Febuxostat

A validated and highly selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of ketorolac tromethamine (KTC) with phenylephrine hydrochloride (PHE) (Mixture 1) and with febuxostat (FBX) (Mixture 2) in bulk drug and in combined dosage forms. The proposed method was based on HPTLC separation of the drugs followed by densitometric measurements of their spots at 273 and 320 nm for Mixtures 1 and 2, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using chloroform-methanol-ammonia (7:3:0.1, v/v) and (7.5:2.5:0.1, v/v) as mobile phase for KTC/PHE and KTC/FBX mixtures, respectively. Linear regression lines were obtained over the concentration ranges 0.20-0.60 and 0.60-1.95 µg band(-1)for KTC and PHE (Mixture 1), respectively, and 0.10-1.00 and 0.25-2.50 µg band(-1) for KTC and FBX (Mixture 2), respectively, with correlation coefficients higher than 0.999. The method was successfully applied to the analysis of the two drugs in their synthetic mixtures and in their dosage forms. The mean percentage recoveries were in the range of 98-102%, and the RSD did not exceed 2%. The method was validated according to ICH guidelines and showed good performances in terms of linearity, sensitivity, precision, accuracy and stability.

A stability–indicating first–derivative spectrophotometric assay of acetazolamide and its use in dissolution and kinetic studies

A simple, rapid, stability–indicating first–derivative spectrophotometric assay procedure for the determination of the degradation products of acetazolamide is described. The dissolution and kinetics of drug degradation in aqueous buffered solutions were studied using the proposed method. Acetazolamide solution exhibited optimum stability at pH 4. The influences of temperature and sonic energy on the degradation of acetazolamide in 0–01 M NaOH solution were also studied. The results showed first–order reaction kinetics, with a degradation rate constant and degradation half–life of 31 times 10‐3 day‐1 and 8–23 days, respectively.

Corrosion inhibition of Neem (Azadirachta indica) leaves extract as a green corrosion inhibitor for Zinc in H2SO4

Abstract The corrosion inhibition of Neem (Azadirachta indica (AZI)) leaves extract as a green inhibitor of zinc corrosion in H2SO4 has been studied using the gravimetric method. The results of the study reveal that the different concentrations of the AZI extract inhibit zinc corrosion and that inhibition efficiency of the extract varies with concentration and temperature.

Development and validation of spectrophotometric and HPTLC methods for simultaneous determination of rosiglitazone maleate and metformin hydrochloride in the presence of interfering matrix excipients

Abstract Two simple methods have been developed and validated for the simultaneous determination of rosiglitazone maleate (ROS) and metformin hydrochloride (MET) in synthetic mixtures and coated tablets in a ratio of 1:250 (ROS:MET). The first method was a spectrophotometric one. The minor component, ROS was determined by measuring the values of absorbance at λmax 312 nm and the D1 amplitudes at 331 nm where MET shows no absorption contribution. However, absorbance interferences from tablet excipients were successfully corrected by D1 at 331 nm zero-crossing technique. Study of spectral interference from tablet excipients was included in the text. Standard curves for Amax and D1 methods were in the concentration range 20.0–80.0 μg mL−1. The major component, MET was determined both in binary mixtures and tablets by measuring its Amax at 236 nm. Extensive dilution eliminated any absorption contribution from the coexisting ROS or tablet matrix. Standard curves showed linearity in the concentration range 4.0–12.8 μg mL−1. The second method was based on high performance thin layer chromatography (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 230 nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using methanol:water:NH4Cl 1% w/v (5:4:1 v/v/v) as the mobile phase. Linear calibration graphs of peak area values were obtained versus concentrations in the range of 0.4–2.0 μg band−1 and 20.0–100.0 μg band−1 for ROS and MET, respectively. According to International Conference on Harmonisation (ICH) guidelines, different validation parameters were verified for the two methods and presented.

HPTLC analysis of ternary mixture containing ketorolac tromethamine, phenylephrine hydrochloride, and chlorpheniramine maleate

ABSTRACT Validated and selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of ketorolac tromethamine (KTC), phenylephrine hydrochloride (PHE), and chlorpheniramine maleate (CPM) in bulk drug and in combined dosage form. The proposed method depends on using HPTLC for separation of the drugs followed by densitometric measurements of their spots at 261 nm. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using chloroform–methanol–ammonia (7.75:2.25:0.1, v/v) as mobile phase. Linear regression lines were obtained over the concentration ranges 0.12–0.50, 0.075–0.27, and 0.09–0.27 µg band−1 for KTC, PHE, and CPM, respectively, with correlation coefficients higher than 0.999. The method was successfully applied to the analysis of the three drugs in their synthetic mixtures and in their dosage form. The mean percentage recoveries were in the range of 98–102% with percentage relative standard deviation values less than 2%. The method was validated according to ICH guidelines and showed good performances in terms of linearity, precision, accuracy, sensitivity, and stability. GRAPHICAL ABSTRACT