The shape and parameters of the EPR spectra in true solutions and micellar solutions of surfactants were different, they also depended on the structure and solubility of the spin probes. Surfactant micelles were anisotropic in viscosity, and different segments of the alkyl chains of surfactant-modeling probes had different dynamic properties. The packing of molecules in micelles was more ordered and compacted at the level of the 5th carbon atom. EPR spectra and/or their parameters changed due to the interaction of surfactant and probe, surfactant and other substances or the sol → gel transitions in solutions of poloxamers.
It has been shown that the formation of a carbomer-based gel did not affect the rotational correlation time of the probe, which did not interact with the carbomer. Parameters of in vitro release of dissolved active substance from gel and liquid differed little; these parameters were also little affected by the difference in apparent viscosity of the gels. The in vitro release of active substance depended on its concentration and the content of hydrophilic non-aqueous solvent.
Density, viscosity and thermodynamics of viscous flow of binary and ternary solutions (for example, water – hexylene glycol, water – ethanol – methylpyrrolidone, water – (propylene glycol – macrogol 400), propylene glycol – macrogol 400, etc.) were studied. The relationship between the structure of the mixed solvent systems and the solubility of certain active substances (mometasone furoate, betamethasone dipropionate, meloxicam etc.), the physical stability of the emulsions o/w as well as in vitro release of penetration enhancers was shown.
Services for pharmaceutical industry:
- Development of medicinal products.
- Study of physicochemical properties of the some medicinal products, which are dispersed system with a liquid, solid or gaseous dispersion medium.
- In vitro release test for evidence of pharmaceutical equivalence:
- Study of metered dose inhalers, in particular, aerodynamic assessment of fine particles.
- Development and validation of analytical procedures for quality control of multicomponent medicines.
- Quality control (HPLC, GC, TLC, absorbtion spectrophotometry – Infrared, ultraviolet and visible, potentiometric titration, particle size distribution by laser diffraction etc.)