Biomedical subjects

G D Ovcharova

Publications and source records attributed to G D Ovcharova.

3 recordsLinked to original sources

PubMed1990

[A potentiometric method of quantitative analysis of rifampicin].

A potentiometric procedure for assay of rifampicin was developed. The procedure implies titration of rifampicin as a monofunctional acid by sodium hydroxide solution (0.1 mol/l) in 75 per cent aqueous methanol. The constant ionic strength of the solution is provided by addition of KCl until its concentration is 0.1 mol/l, the titrant concentration being 10 times higher than the antibiotic concentration in the solution. This provides a precise determination of the concentration ionization constant of the antibiotic as a monofunctional acid (pKa 7.33 +/- 0.01) and an insignificant dilution of the antibiotic solution during the titration promoting precise and reproducible results. The procedure error is 0.20 per cent. The variation coefficient is 0.27 per cent.

Hydrochloric Acid↗

PubMed1984

[Kinetics of ampicillin breakdown in the solid state].

The degradation kinetics of solid sodium ampicillin, ampicillin trihydrate and anhydrous ampicillin was studied in relation to the disintegration level of the powder before and after its screening by the particle size. It was shown that the effect of the powder disintegration level on the degradation rate constant proceeded by the spherical model and the reaction of the antibiotic degradation proceeded according to the equation of the first order reaction. The degradation rate constants of the total fractions and the fractions with the particle size of 60, 80 and 100 micron at elevated and room temperatures and their half-lives were evaluated. Different mechanisms of degradation of three ampicillin forms were shown on the basis of the dependence of the degradation rate constant on the temperature and the data of thin-layer chromatography. Higher stability levels of ampicillin powder with the particle size of 100 micron and anhydrous ampicillin in comparison with sodium ampicillin and ampicillin trihydrate were observed. This allows recommending anhydrous ampicillin for preparation of oral dosage forms.

Ampicillin↗

PubMedDate not supplied

[Correlation between crystalline structure and biological properties of sodium cefazolin].

Antimicrobial activity and toxicity of four polymorphic forms of sodium cefazolin were studied in comparison to those of the initial cefazolin. The observed changes reflecting a broader antimicrobial spectrum and low toxicity of one of the forms as compared with those of the initial cefazolin could serve as a prerequisite to successful screening of more active crystalline forms of the antibiotic aimed at designing the drug with better therapeutic properties.

Animals↗