Physico-Chemical nanomaterials science

Microsponges in tretinoin topical drugs
Straszak D.1, Matosiuk D.1, Tabin M.2
1 Department of Synthesis. And Chemical Technology of Pharmaceutical Substances, Medical University in Lublin, Chodźki 4a, Lublin 20-093, Poland.
E-mail: dominik.straszak@gmail.com
2 Department of Endocrinology, Diabetology and Metabolic Diseases, 4th Military Clinical Hospital in Wrocław, Weigla 5, Wrocław, 50-981, Poland.

     Viscosity is an extremely important physicochemical property that characterizes semi-solid drug forms for external use. This parameter determines the accuracy and ease of application as well as the homogeneity of the drug, and thus indirectly affects the release of the active substances from the vehicle. Research is continuing on the formulation of new therapeutic systems that increases bioavailability, and thus pharmacological effectiveness of the active substances administered externally. An interesting direction of research are topical delivery systems based on microsponges that are built of highly porous microspheres. The use of microsponges in preparations of creams or gels affects their rheological properties and allows for a stable and constant release of active substances applied on the skin, and thus increases the effectiveness and safety of the therapy.
     The aim of the study was to determine viscosity of drugs with various vehicle compositions containing tretinoin at a concentration of 0,1%. The study was performed for self-prepared pharmaceutical ointments in accordance with pharmacopoeial requirements, in which the vehicle was white petrolatum or eucerine and three registered medicinal products in the form of cream, gel and microsphere gel containing cross-polymer methyl methacrylate/glycol dimethacrylate. The study was performed using a rotational viscometer Viscotester 6 (Thermo Scientific, Germany). Measurements were made at 37°C at a rotational speed of 100 rpm, and dynamic viscosity values ​​were read at 30 seconds. The determined mean value of viscosity from three measurements was 15871 mPa x s for ointment based on white petrolatum, 19923 mPa x s for ointment based on eucerine, 12099 mPa x s for cream, 8200 mPa x s for gel and 5239 mPa x s for microsphere gel.
The differentiation of the results indicates that vehicle composition affects the value of dynamic viscosity which translates into the diversification of pharmaceutical properties of the drug.