FRACTAL ANALYSIS OF BETA-CYCLODEXTRIN-INDOMETHACIN PARTICLES COMPACTED BY ULTRASOUND

An association between indomethacin and beta-cyclodextrin (beta-CD) wa s obtained by compacting a 1:2 molar physical mixture by ultrasound. T he product prepared by this technique was compared with the initial ph ysical mixture and with materials having the same composition but prep ared by a simple compaction and kneading process. The samples examined by scanning electron microscopy revealed morphological differences re lated to the methods of preparation. In particular the material obtain ed by ultrasound had a smooth surface and on milling produced particle s of uniform size; moreover EDAX analysis (energy dispersion analysis by X-rays) also revealed a homogeneous distribution of the two compone nts in each particle examined. Surface fractal dimension of the surfac e of these particles is very low, suggesting the presence of a regular and smooth surface whereas the sample obtained by kneading had a high er value. The reactive dimension related to dissolution was much highe r than the corresponding surface dimension in all cases and had compar able values for all samples regardless of the techniques used. This be havior was attributed to the hydrophilicity of beta-CD, which levels t he differences during dissolution and which could be originated by sur face imperfections. Experimental results suggested that the material o btained by ultrasound had a dissolution rate comparable to that measur ed with the kneaded material. The use of ultrasound, however, can both reduce the production time and improve the homogeneity of the associa tion between indomethacin and beta-CD.