PubMed · 14887762
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1951. [Gordeev's solution].. https://pubmed.ncbi.nlm.nih.gov/14887762/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The dissolution profiles and solubilities of three quinolonic drugs (oxolinic, pipemidic, and nalidixic acids) in different solvent mixtures were studied. The behavior of the solid phase, during solubility experiments was in-depth investigated with the aim of detecting possible crystalline modifications, such as polymorphic transitions or solvate formations, that might modify drug stability and/or solubility properties. In order to test the influence of both the nature and polarity of the co-solvents, aqueous and non-aqueous binary mixtures have been prepared by using Lewis base (dioxane and ethyl acetate) and amphiprotic co-solvents (ethanol and water). Differential scanning calorimetry (DSC), hot stage microscopy, IR spectroscopy and X-ray powder diffraction were used in combination with solubility and dissolution studies to characterize and investigate the solid state properties of the original powders and the corresponding ones at equilibrium with the different pure solvents and solvent mixtures examined. The solid phases of nalidixic and oxolinic acids did not show any change after equilibration with the various pure solvents or binary solvent mixtures, regardless the chemical nature of the examined solvents. On the contrary, in the case of pipemidic acid, the different analytical techniques used to characterize the drug solid state enabled identification of a solvated form at equilibrium with pure dioxane and a trihydrated form in aqueous mixtures of water with both ethanol (amphiprotic) or dioxane (Lewis base) in a concentration range from 10 to 100% water.
Vitamin A acid (VAA) was firstly dissolved in chloroform, and then the organic solution containing the samples was mixed with silver sol at the desired concentration. After sufficient shaking, collect SERS spectra of VAA with silver sol layer solution. The attribution of the peaks was illustrated by comparing SERS spectra with NR (Normal Raman) spectra, and the mechanism and orientation of adsorption were also discussed according to the peaks which was absent in NR spectrum but observed in SERS spectrum. To verify the feasibility of the method for the quantitative analysis, SER spectra at different concentration of VAA were collected. The intensities measured with the band at 1583 cm(-1) were plotted as a function of concentration. It was found that an effective limit for the detection of VAA could be as low as to 1.0 x 10(-7) mol x L(-1), the calibration curve was linear in the range from 1.0 x 10(-6)-5 x 10(-5) mol x L(-1). The proposed method has the potential to quantitative assay of the drugs having SERS effects but undissolvable in water.
The effect of steam sterilization (dwell@121 degrees C) on the apparent viscosity of solutions of carbomer 940P, guar gum, hydroxyethylcellulose (HEC), and xanthan gum was studied. Guar gum and carbomer 940P could be steam sterilized for 30 min without any change in the apparent viscosity. Steam sterilization of HEC and xanthan gum resulted in a substantial decrease in the apparent viscosity and the desirable shear-thinning rheology. The addition of sodium chloride to either polymer prior to steam sterilization diminished the effect of sterilization on the rheology. The apparent viscosity of xanthan solutions was not significantly affected if the solution was made isotonic with sodium chloride (0.15 M). The addition of sodium chloride to xanthan gum after steam sterilization resulted in full recovery of the initial rheological properties. Carbomers, guar gum, and xanthan (in 0.15 M NaCI) are candidates for use in pharmaceutical solutions/suspensions that are subjected to steam sterilization.