Biomedical subjects

H M Abdou

Publications and source records attributed to H M Abdou.

4 recordsLinked to original sources

PubMed1979

Kinetics and mechanism of reaction of m-nitrobenzhydrazide and other hydrazines with acetic acid.

A comprehensive kinetic study was conducted of the reactions of m-nitrobenzhydrazide and some other hydrazines with acetic acid. The overall reaction rate for all of the compounds studied followed pseudo-first-order kinetics. The temperature dependence of the m-nitrobenzhydrazide degradation reaction was determined. The reaction rate dependence on the acetic acid concentration was found to be close to first order. High-pressure liquid chromatography was used extensively in identifying and measuring the appearance or disappearance rates of m-nitrobenzhydrazide degradation products in acetous solution. With m-nitrobenzhydrazide, the major degradation products were N,N'-bis(m-nitrobenzoyl)hydrazine, N-acetyl-N'-m-nitrobenzoylhydrazine, diacetylhydrazine, and hydrazine. The concentration profiles of these products in solution suggested a complex mechanism by which hydrazides react with acetic acid. All eight rate constants at 61 degrees in the suggested mechanism were calculated by an approximation method based on experimental data. The findings in the present study indicate that acetic acid is to be avoided as a solvent for hydrazine derivatives.

Acetates↗

PubMed1979

Analysis of fludrocortisone acetate and its solid dosage forms by high-performance liquid chromatography.

A newly developed reversed-phase high-performance liquid chromatographic assay and test method for determining content uniformity are described for fludrocortisone acetate. The method is stability indicating and separates most known degradation products and impurities. In addition, the method is simple, sensitive, accurate, and relatively free of interferences. The coefficient of variation for multiple weight assays is between 0.3 and 1.8%.

Chromatography, High Pressure Liquid↗

PubMed1978

Semiautomated system for high-pressure liquid chromatographic determination of dissolution rate of fludrocortisone acetate tablets.

A new semiautomated high-pressure liquid chromatographic (HPLC) system is described to determine the dissolution rate of fludrocortisone acetate tablets. The system uses a miniaturized dissolution basket and shaft assembly having the same geometry as that given in USP XIX. This reduced size permits use of smaller volumes of dissolution medium, allowing most very low dose oral solid dosage forms to be handled. The USP dissolution kettle was also replaced with a new miniaturized vessel that continuously filters the sample solution before it enters the flow system. Volumes of dissolution medium as small as 15 ml can be accommodated, depending on the sensitivity of the assay employed and the solubility of the drug substance under study. The concentration of fludrocortisone acetate in solution was monitored by a new HPLC system employing a reversed-phase column compatible with the aqueous dissolution medium used. A comparative dissolution study of different lots was made using different basket rotation speeds.

Autoanalysis↗

PubMed1976

Computerized automated system for determining dissolution rate profiles for solid dosage forms.

A unique automated system was developed for the measurement of dissolution rates of tablets and capsules. This system, which adheres to principles set forth in the compendia, can test six dosage forms simultaneously. It is modular in form and capable of maintaining sink conditions, and it can handle any type of chemistry amenable to an automatic analyzer. In addition to the usual dissolution apparatus, the system includes a 12-channel combination sampling and solvent addition pump, a sequence control module, pertinent automated analyzer components, a spectrophotometer or fluorometer, an optional recorder, a specially designed digitizing system, and a teletype equipped with a paper tape punch reader and acoustic coupler. Each dissolution flask is automatically sampled every 6 min. Standards may be run either before or after the samples. Since dissolution, sampling, chemistry, and readout are all accomplished simultaneously, the complete test time is essentially reduced to the dissolution time itself. At the completion of sample dissolution, raw dissolution profile data are on the punched paper tape ready for computer processing via a time-sharing system. Developed software provides for the printout of a complete test report in less than 15 min.

Capsules↗