Within the framework of pre-formulation studies, the paper evaluates the rheological properties of hydrogels whose gel-forming substance is a polymer supplied by the firm J. Rettenmaier & SöhneGMBH+CO. It is VIVASTAR® P 5000, a modified derivate of carboxymethyl starch. The evaluation of rheological properties included hydrogels with 1.5, 2.0 and 2.5 w % of VIVASTAR® P 5000. The highest viscosity was shown by the hydrogel with 2.0% concentration of the polymer. The system without and with the model drug with a local anaesthetic effect was thixotropic. From the viewpoint of topical administration, VIVASTAR® P 5000 in 2.0% is optimal for hydrogel formulation.

        Key words: VIVASTAR® P 5000 – hydrogels – model drug XXII B – rheological properties