M. E. Abdel-Hamid

Utility of iodine and 7,7,8,8-tetracyanoquinodimethane for determination of terfenadine.

Simple and sensitive spectrophotometric methods for the assay of terfenadine are described. The first is based on the reaction of terfenadine with iodine to give a molecular charge-transfer complex, the terfenadine acting as an n-electron donor and iodine as a sigma-electron acceptor. The second depends on the formation of a highly coloured stable radical anion between terfenadine and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a pi-electron acceptor. Beers law is obeyed over the terfenadine concentration range 0.2-1.2 mg/100 ml. The proposed methods have been successfully applied to the analysis of commercial terfenadine tablets.

Simultaneous High-Performance Liquid Chromatographic Assay of Acetaminophen, Acetylsalicylic Acid, Caffeine, and D-Propoxyphene Hydrochloride

Abstract A reversed phase high-performance liquid chromatography (HPLC) method for simultaneous measurement of acetaminophen (I), acetylsalicylic acid (II), caffeine (III) and d-propoxyphene (IV), using phenacetin (V) as an internal standard was developed. Using a 6.5 μ C-8 reversed phase column (RPP) with a mobile phase consisting of 0.01M sodium acetate solution: methanol (85:15%) at pH 4.1 enabled the Chromatographic separation of the four components in about 12 min. Quantitation was achieved by measuring the peak height ratio of each component relative to the internal standard. the validity of the developed method was tested by analyzing laboratory-prepared mixtures containing the four components in various proportions. Assay precision and sensitivity have been established for each component. the developed method proved to be stability-indicating as it can be applied to monitor salicylic acid as a degradation product in acetylsalicylic acid samples.

A RAPID HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHY ASSAY OF GLIBENCLAMIDE IN SERUM

A rapid high‐performance liquid chromatography (HPLC) determination of glibenclamide in human serum is described. Serum samples to which flufenamic acid had been added as internal standard were treated with aceto‐nitrile as a protein precipitant. After centrifugation, separation and recon‐stitution, the redissolved residue was eluted from 5 μ Spherisorb C‐8 reversed phase column at ambient temperature using a mobile phase consisting of acetonitrile‐water (45: 55 v/v) at pH 3·7‐3·8 and pumped at a flow rate 2 ml/min. The effluent was monitored at 230 nm. The analysis time was no longer than 12min. A linear relationship between the peak height ratio (glibenclamide/flufenamic acid) and concentration was obtained in the range 20–400 ng/ml. A typical calibration curve has a regression equation y= 0·0035x + 0·015 (r = 0·9999). The detection limit of glibenclamide in serum was 20 ng/ml. The mean recovery of drug from serum samples spiked with known amounts of glibenclamide was 96·77%. Within‐day and between‐day coefficients of variation were 1·6‐4·0% and 1·4‐3·5%, respectively. Stability testing indicated that glibenclamide was stable for at least 10 days in serum — 20°C. The method developed was applied to determine some pharmacokinetic parameters after the oral administration of 5 mg glibenclamide tablets to a human volunteer.

IN VITRO AND IN VIVO EVALUATION OF SUSTAINED-RELEASE AND ENTERIC-COATED MICROCAPSULES OF DICLOFENAC SODIUM

AbstractThis work examines the release of diclofenac sodium from ethylcellulose (EC) microcapsules made up of different drug to polymer ratios. The release process was found to follow the Higuchi square root equation and not the zero-order or first order equations. However, for drug to polymer ratio of 1:1, a critical time (θ) was reached beyond which the release rate was lower than that predicted on the basis of the Higuchi square root equation. Dissolution experiments in 0.1N HCL revealed that less than 1.5% of the encapsulated drug was released in 6 h. This finding indicates the suitability of the EC microcapsules for enteric-coated preparations. The in vitro release of diclofenac sodium from microcapsules of different drug to polymer ratios was compared with that from a commercial sustained-release product. A distinct similarity between the release profile of the commercial product with that obtained for the 1:2 drug to polymer microcapsules was noted. The in vivo work included determination of the se...

A Stability-Indicating Hplc Analysis of Famotidine and Its Application to Kinetic Studies

Abstract A stability-indicating HPLC analytical method has been developed for the determination of the H2-receptor antagonist, famotidine in the presence of its degradation products. the method utilizes reversed phase chromatography with UV detection and internal calibration techniques. the mobile phase was comprised of 84% ammonium acetate buffer (pH 2.9) and 16% acetonitrile and pumped at a flow rate of 1.5 ml/min. Quantitation was performed by measuring the peak height ratio of drug to internal standard (salicylic acid). the limit of famotidine detection was determined to be 10 ng (0.4 ug/ml) with a signal to noise ratio of 3:1. Within day coefficient of variation of the method was 2.22% (2.5 μg/ml) and 0.82% (10 μg/ml). Between day coefficient of variation based on the slopes of daily prepared standard curves was 4.70%. the developed method was used to determine the drug content of famotidine tablets. Further, it was used to investigate the kinetics of degradation of the drug in an acidic solution.

Simultaneous High-Performance Liquid Chromatographic and First-Derivative Spectrophotometric Determination of Amitriptyline Hydrochloride and Chlordiazepoxide In Capsules

Abstract Rapid, precise, accurate and specific high-performance liquid chromatographic and first-derivative spectrophotometric procedures were described for the simultaneous analysis of amitriptyline and chlordiaze-poxide in two-component capsule formulations. A reversed phase Micropack MCH-5 (CI8) column with a mobile phase composed of acetonitrile/water in a ratio (50:50) at pH3 and containing 0.01 M sodium-n-octane sulfonate separated amitriptyline, chlordiazepoxide and diazepam (internal standard). the drugs were detected at 230 nm at ambient temperature. the trough amplitudes in the first derivative spectrophotometric spectra at 245 nm and 282 nm were selected to determine amitriptyline and chlordiazepoxide. Commercial capsules and laboratory-prepared mixtures containing both drugs in different proportions were assayed using the developed methods. the results were of comparable accuracy as indicated by the statistical analysis of data using t-test and F-test.

Physico-chemical characterization of a new salt of ibuprofen

A new salt of ibuprofen was prepared by reaction with t-butylamine; its formation was confirmed by IR and 1H-NMR spectroscopy. The salt was characterized by thermoanalytical, X-ray powder diffraction and solubility studies. The salt was found to be 1.5 times more soluble in water than was ibuprofen, with an enthalpy of solution of -8.84 kcal mol-1.

HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF PROPRANOLOL AND 4‐HYDROXYPROPRANOLOL IN SERUM

A simple, sensitive and selective high performance liquid chromatographic method for the analysis of propranolol and its major metabolite 4‐hydroxypropranolol is developed. The drugs and the internal standard, quinidine, were extracted from serum with ether at pH 10. The latter was evaporated and the residue was dissolved into phosphoric acid solution.

SIMULTANEOUS HIGH-PRESSURE LIQUID CHROMATOGRAPHIC ANALYSIS OF AMPICILLIN AND CLOXACILLIN IN SERUM AND URINE

A rapid, specific and sensitive high pressure liquid chromatographic (HPLC) assay for the simultaneous determination of ampicillin and cloxacillin in serum and urine is developed.

Rapid High Performance Liquid Chromatographic Determination of Ampicillin in Human Urine

Abstract A rapid, sensitive and specific HPLC assay for the determination of ampicillin in human urine is developed. Ampicillin was directly measured in human urine at 225 nm using a reversed phase column (Synchropack RP-P) and a mobile phase composed of (1:9 methanol-sodium acetate solution, 0.01 M, pH 4). The analysis required no longer than 10 min. Linear correlation between the peak height ratio of ampicillin to cefoxitin sodium (internal standard) and ampicillin concentration in urine over the range 10–100 μg ml−1 was obtained. The developed method proved to be advantageous as it monitors ampicillin level in urine. Moreover, the urinary excretion of ampicillin in human subjects after an oral administration of 500 mg ampicillin capsules was established using the proposed method.