CONICET | Buscador de Institutos y Recursos Humanos

The viscosity and texture of semi-solid pharmaceutical forms of topical applications are of paramount importance to ensure a good distribution of the product on the skin. Liquid crystals, being formed by a fat-soluble and a water-soluble fraction, allow both fatsoluble and water-soluble drugs to be incorporated into their structures. The objective of this work was to evaluate the rheological profiles that had two emulsifying systems with liquid crystals, one of them without active substance (a) and the other with active substance (b), and to determine whether the properties of the latter were within values to be used as a topical application medicine. The pharmaceutical active ingredient that was incorporated was Miconazole, a fat-soluble substance with antifungal activity. The samples were prepared in triplicate. The rheological characterization was performed with a Brookfield viscometer at 25ºC. Determinations were made after 48 h of preparation of the emulsions and repeated at 6 months. All samples had profiles of similar characteristics being plastic bodies with thixotropy. For the 2.5 s-1 velocity gradient, the viscosity values obtained were for the sample (a) of one-way 830 cp and lap 670 cp, while the sample (b) present of one-way 720 cp and lap 600 cp. The yield, viscosity, and thixotropy values of the sample (a) were slightly higher than the values presented by the sample (b). This decrease in rheological values in the sample (b) could be related to the active substance Miconazole being incorporated into the hydrocarbon chains of the crystalline structures that form a multilayer that surrounds both the emulsion drops and the secondary drops, causing defects that would contribute to lowering those values. However, the sample (b) maintains a suitable viscosity and stability for being applied to the skin.