Osama H. Abdelmageed

Spectrophotometric determination of clotrimazole in bulk drug and dosage forms

A simple, specific, rapid and sensitive spectrophotometric method has been developed for the assay of clotrimazole, in bulk drug and its pharmaceutical preparations. This method is based on the ion-pair complex reaction of clotrimazole and methyl orange in aqueous methanol, and in the presence of citric acid. The chromogen, being extractable with chloroform, could be measured quantitatively at 422 nm. All variables were studied to optimize the reaction conditions. Regression analysis of beers plot showed good correlation in a general concentration range of 2-14 mu/ml. The proposed method has been successfully applied for the analysis of the bulk drug and its dosage forms such as powder, vaginal tablets, topical solution and creams. No interference was observed from betamethasone dipropionate (Lotriderm cream) or dexamethasone acetate and azidamphenicol (Baycuten cream) or other common pharmaceutical adjuvants. In addition, this method was also found to be specific for the analysis of clotrimazole in the presence of its hydrolytic products as well as imidazole, as a possible impurity.

Selective spectrophotometric determination of ascorbic acid in drugs and foods

A new analytical method was developed for the determination of ascorbic acid. The method is based on the reaction of ascorbic acid with 4-chloro-7-nitrobenzofurazane (NBD-Cl) in the presence of 0.2M sodium hydroxide, where a bluish green colour (lambda(max) 582 nm) is developed after dilution with 50% (v/v) aqueous acetone solution. Beers law was obeyed in a concentration range of 5-20 microg ascorbic acid/ml with a good correlation coefficient (r = 0.9990). The method was found to be highly specific for the determination of ascorbic acid in the presence of dehydro-ascorbic acid, all other vitamins and minerals possibly present in multivitamin preparations, rutin, salicylamide, acetyl salicylic acid, paracetamol, caffeine, phenylephrine hydrochloride and dipyrone. Moreover, the proposed procedure was also successfully applied for the determination of ascorbic acid in some canned and fresh fruit juices, some vegetables and infant milk products without interference from coloured and other substances present in the plant extracts.

Kinetic spectrophotometric determination of certain cephalosporins in pharmaceutical formulations.

A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 610 nm. The initial rate and fixed time (at 3 minutes) methods are utilized for construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 5–15 μg mL−1 and 5–25 μg mL−1 using the initial rate and fixed time methods, respectively. The results are validated statistically and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. Statistical comparisons of the results with the reference methods show the excellent agreement and indicate no significant difference in accuracy and precision.

Spectrofluorimetric determination of certain antidepressant drugs in human plasma

BackgroundCertain antidepressant drugs namely Sertraline hydrochloride, Fluoxetine hydrochloride, Paroxetine hydrochloride, Thioridazine hydrochloride and Amineptine hydrochloride were studied throughout this work using spectrofluorimetric method.MethodsThe spectrofluorimetric method is based on the charge-transfer reaction of these drugs as n-electron donors with 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π-electron acceptor. The drug-TCNQ complexes showed excitation maxima ranged from 290-301 nm and emission maxima ranged from 443-460 nm.Results and discussionThe different experimental parameters affecting the formation and stability of the complexes were carefully studied and optimized. The calibration plots were constructed over the range of 50-450 ng mL-1 for Fluoxetine and Sertraline, 50-550 ng mL-1 for Paroxetine, 50-650 ng mL-1 for Thioridazine and 50-750 ng mL-1 for Amineptine. The proposed method was validated according to ICH and USP guidelines with respect to specificity, linearity, accuracy, precision and robustness.ConclusionA simple, reliable, sensitive and selective spectrofluorimetric method has been developed for determination of certain antidepressant. The proposed method was successfully applied to the analysis of the cited drugs in dosage forms. The high sensitivity of the proposed method allows determination of investigated drugs in spiked and real human plasma.

Spectrophotometric Determination of Nifedipine and Nicardipine in their Pharmaceutical Preparations

A sensitive and selective spectrophotometric method was developed for determination of nifedipine (NIF) and nicardipine (NIC) in their pharmaceutical preparations. The method based on a rapid reduction of the nitro to primary amino groups using zinc dust and hydrochloric acid. The resulting primary aromatic amine was subjected to a condensation reaction with p-dimethyl amino benzaldehyde to produce a yellowish-green color of Schiff’s bases which quantified spectrophotometrically at the absorption maxima of 434 and 441 nm for NIF and NIC, respectively. Beer’s law was obeyed in the concentration ranges 2.0 to 12.0 μg/mL with a limit of quantitation 1.4 and 1.9 μg/mL and the mean percentage recoveries 98.2±0.3 to 99.5±0.3% NIF and NIC, respectively. The proposed methods were successfully applied to assay NIF and NIC in their capsules and tablets.

New valid spectrofluorimetric method for determination of selected cephalosporins in different pharmaceutical formulations using safranin as fluorophore

A new validated spectrofluorimetric method has been developed for the determination of some cephalosporins namely; cefepime, cefaclor, cefadroxil, cefpodoxime and cefexime. The method was based on the reaction of these drugs with safranin in slightly alkaline medium (pH 8.0), to form ion-association complexes. The fluorescent products were extracted into chloroform and their fluorescence intensities were measured at 544-565 nm after excitation at 518-524 nm. The reaction conditions influencing the product formation and stability were investigated and optimized. The relative fluorescence intensity was proportional to the drug concentration in the linear ranges of 0.15-1.35, 0.35-1.25, 0.35-1.25, 0.20-1.44 and 0.20-1.25 μg/mL for cefepime, cefaclor, cefadroxil, cefpodoxime proxetil and cefexime, respectively. The detection limits were 40, 100, 100, 60 and 70 ng/mL, respectively. The performance of the developed method was evaluated in terms of Students t-test and variance ratio F-test to find out the significance of proposed methods over the reference spectrophotometric method. Various pharmaceutical formulations were successfully analyzed using the proposed method and the results were in good agreement with those of the previously reported methods.

Chiral separation of perindopril erbumine enantiomers using high performance liquid chromatography and capillary electrophoresis

Two separation methods were developed for the determination of S- and R-perindopril tert-butylamine (erbumine salt) (PER): high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). The HPLC method uses a chiral stationary phase (CSP), ChiraDex column constituting β-cyclodextrin chemically bonded to spherical silica gel particles. The mobile phase consisted of phosphate buffer (50 mM, pH 3.0) and acetonitrile (45:55 v/v). The flow rate was 1.0 mL min−1 and the detection wavelength was 210 nm. In CE, 2-hydroxylpropyl-β-cyclodextrin (10 mM) was used as a chiral selector. It was added to the background buffer composed of phosphate buffer (100 mM, pH 7.0) and methanol (15% v/v). The applied voltage was 15 kV and the detection was carried out using a diode array detector. All factors affecting the chromatographic or electrophoretic separations were studied and optimized. The linear concentrations ranged from 5–150 and 25–800 μg mL−1 with detection limits of 2.3 and 14.7 μg mL−1 for HPLC and CE methods, respectively. The methods were validated according to ICH and USP guidelines. The suggested methods were applied for the determination of S-PER in bulk powder and commercial tablets containing PER erbumine racemate.

Spectrofluorimetric determination of certain biologically active phenothiazines in commercial dosage forms and human plasma.

A validated simple and sensitive spectrofluorimetric method was developed for the determination of chlorpromazine hydrochloride, promethazine hydrochloride, trifluperazine hydrochloride, thioridazine hydrochloride, perazine maleate and oxomemazine. The method was based on condensation of malonic acid/acetic anhydride (MAA) under the catalytic effect of the tertiary amine moiety of the studied phenothiazines to provide a deep yellow to brown colour with green fluorescence. Relative fluorescence intensity of the products was measured at λ exc 398 nm and λ em 432 nm. Different variables affecting the reaction were studied and optimized. The method was successfully applied for the determination of the studied drugs in commercial dosage forms. The lower detection limits allowed the application of this method for the determination of the compounds in plasma as an example of a biological fluid. In addition, the method was considered specific for the determination of tertiary amines in the presence of primary and secondary amines; as a result, it was deemed suitable for the determination of the cited drugs in the presence of their degradation products resulting from N-dealkylation or oxidation of the corresponding sulphoxides or sulphones.

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY, TLC-DENSITOMETRY, AND FIRST-DERIVATIVE SPECTROPHOTOMETRY FOR SIMULTANEOUS DETERMINATION OF AMLODIPINE AND PERINDOPRIL IN BULK POWDER AND ITS TABLETS

Three simple, sensitive, and specific methods were developed for simultaneous determination of amlodipine besylate (AML) and Perindopril Erbumine (PER) without previous separation. The first method was dependent on the first derivative of the ratio spectra by measuring the amplitudes at 348 nm for amlodipine using 50 µg mL−1 of perindopril as a divisor and at 227 nm for perindopril using 30 µg mL−1 of amlodipine as a divisor. The second method was based on ion-pair RP-HPLC. Satisfactory resolution was achieved using RP-C18 chromatographic column Zorbax Extend column and a mobile phase consists of potassium dihydrogen phosphate buffer (0.05 M, pH 3.0 ± 0.02 adjusted by orthophosphoric acid): acetonitrile 30:70 v/v at a flow rate 1 mL/min using 0.002 M sodium heptanesulfonate in the aqueous phase. UV detection was performed at 215 nm. The third method was based on TLC; the separation was carried out on Fluka TLC aluminum sheets silica gel 60 F254, using n-butanol:water:glacial acetic acid (4:5:1, v/v/v) as the mobile phase. The validation of the proposed methods was applied according to ICH guidelines and LOD and LOQ were calculated. The suggested methods were successfully applied for the determination of the cited drugs in bulk powder and commercial tablets.

Spectrophotometric and spectrofluorimetric methods for determination of certain biologically active phenolic drugs in their bulk powders and different pharmaceutical formulations

Two simple and sensitive spectrophotometric and spectrofluorimetric methods for the determination of terbutaline sulfate, fenoterol hydrobromide, etilefrine hydrochloride, isoxsuprine hydrochloride, ethamsylate, doxycycline hyclate have been developed. Both methods were based on the oxidation of the cited drugs with cerium (IV) in acid medium. The spectrophotometric method was based on measurement of the absorbance difference (ΔA), which represents the excess cerium (IV), at 317nm for each drug. On the other hand, the spectrofluorimetric method was based on measurement of the fluorescent of the produced cerium (III) at emission wavelength 354nm (λexcitation=255nm) for the concentrations studied for each drug. For both methods, the variables affecting the reactions were carefully investigated and the conditions were optimized. Linear relationships were found between either ΔA or the fluorescent of the produced cerium (III) values and the concentration of the studied drugs in a general concentration range of 2.0-24.0μgmL-1, 20.0-24.0ngmL-1 with good correlation coefficients in the following range 0.9990-0.9999, 0.9990-0.9993 for spectrophotometric and spectrofluorimetric methods respectively. The limits of detection and quantitation of spectrophotometric method were found in general concentration range 0.190-0.787 and 0.634-2.624μgmL-1respectively. For spectrofluorimetric method, the limits of detection and quantitation were found in general concentration range 4.77-9.52 and 15.91-31.74ngmL-1 respectively. The stoichiometry of the reaction was determined, and the reactions pathways were postulated. The analytical performance of the methods, in terms of accuracy and precision, were statistically validated and the results obtained were satisfactory. The methods have been successfully applied to the determination of the cited drugs in their commercial pharmaceutical formulations. Statistical comparison of the results with the reference methods showed excellent agreement and proved that no significant difference in the accuracy and precision.