University of Szeged Department of Pharmaceutical Technology Eötvös u. 6 H-6720 Szeged Hungary Eötvös u. 6 H-6720 Szeged Hungary
Budapest University of Technology and Economics Research Group for Technical Analytical Chemistry of the Hungarian Academy of Sciences & Institute of General and Analytical Chemistry Szent Gellért tér 4 H-1111 Budapest Hungary Szent Gellért tér 4 H-1111 Budapest Hungary
University of Szeged Department of Medical Informatics Korányi fasor 9 H-6720 Szeged Hungary Korányi fasor 9 H-6720 Szeged Hungary
The extents of the protective effects of coating films on the surface of crystals were determined. Three different samples
were made with different quantities of coating fluid (Sepifilm LP 010 in 10% aqueous solution). Since the atomizing rate was
constant, the coating time increased in parallel with the volume of coating fluid applied. The direct measurement of film
thickness and smoothness is very difficult, and therefore indirect methods were used. Dimenhydrinate was chosen as model drug;
this is a heat-sensitive antihistamine with a low melting point. This temperature can be reached during the tableting process.
The behaviour of samples on exposure to heat was examined by differential scanning calorimetry. The water uptakes of the samples
were determined with an Enslin apparatus. Plasticity was studied with an instrumented tablet machine. These indirect methods
(thermal conductivity, water uptake and plasticity measurements) revealed connections between the results of the various experiments.
An overlong coating time decreased the protective effect of the coating film.