R.A. Lavrenchuk, I.V. Sakaeva, E.I. Sakanyan, E.B. Nechaeva, L.L. Kojemyakina

This article describes methods of viscosity determination of plasma substitute infusion solutions (for example, hydroxyethyl starch solutions), and experimental testing methods for determining viscosity. Plasma substitutes constitute a significant part of large-volume parenterals. Most of the plasma substitutes are aqueous solutions of hydroxyethyl starch of different molecular masses. Hydroxyethyl starch alter the rheological properties of solutions. For characterization of the rheological properties of the some medicines can be determined viscosity of different types. In some cases, the viscosity can further describe the molecular-mass characteristics of the active ingredients. These approaches are described in the actual domestic and in leading international documents and compendias. Analysis of the approved specifications showed both separately and jointly, using such characteristics as «Intrinsic viscosity» and «Relative viscosity» in its assessment of the rheological properties of the drug infusion of hydroxyethyl starch. In particular, use of the parameter «Intrinsic viscosity» in the analysis of plasma substitute solutions of hydroxyethyl starch allows evaluation of the viscosity of the solution and evaluation of the value of average molecular weight of the active pharmaceutical ingredient. In determining of this parameter are particularly important the analysis conditions and equipment used. In particular, the description of methods of determination, you must specify the exact temperature. The experimental results showed that temperature changes the viscosity of hydroxyethyl starch. Viscosity change was greater at higher concentrations of hydroxyethyl starch.