USE OF FRACTAL DIMENSIONS IN THE STUDY OF EXCIPIENTS - APPLICATION TOTHE CHARACTERIZATION OF MODIFIED LACTOSES

In this paper, the morphological and surface characteristics of lactos e and coated lactose particles are investigated, continuing with the u se of SEM descriptors and fractal dimensions to characterize powder pa rticles. The coating materials were different acrylic polymers of the Eudragit(R) type. The size parameters of lactose and coated lactoses i ndicated that the particle forms deviated from irregular or acicular f orms. Shape factor data of coated substances obtained demonstrated tha t these particles presented regular contours. This fact signifies that lactose particles without coating treatment present irregular profile s with patent edges implying poor flow properties. The aspect ratio va lues of coated lactoses were close to unity and smaller than that show ed by lactose. It is concluded that the polymer particles are placed o n the irregularities of lactose particles, smoothing the roughness of the excipient surface. The fractal dimensions calculated from the slop e of Richardson plots were 1.11 for lactose and 1.04, 1.05 and 1.08 fo r coated lactoses. These results are consistent with the shape paramet ers and flow properties. Some interesting relationships between SEM de scriptors and a number of theological properties have been found.