Segregation of mixtures is a major problem in pharmaceutical industry for which we do not possess a standard solution. It has the most significant impact in process of direct tableting. In this process raw mixtures of the active pharmaceutical ingredient and excipients are used. During the production the mixtures are exposed to different mechanical stresses, which cause segregation of particles. Every deviation in homogeneity of mixture leads to the difference in uniformity of content of a single dosage form. There are different types of mixtures, some are very delicate to handle and the others can retain their homogeneity even at more harsh conditions. Complexity of the system is the reason why we can not predict the level of segregation. Segregation data of mixtures is experimentally determined. There are situations in which we can not prepare mixtures that are robust enough. And we must add additional process of granulation before tableting. Every extra process is connected with higher cost of production and there exists a higher possibility of contamination of the product. This master thesis was devoted to examination of segregation properties of different types of lactose. We have compared commercially available lactoses with a modified lactose which we prepared at the faculty. All examined excipients are appropriate for the usage in the process of direct tableting, because they exhibit good compressibility, compactness and flowing properties. Commercially available lactoses which we examined were Tabletose® 70 and Flowlac® 100. Modified lactose has been prepared by spherical crystallisation with a method solvent, anti-solvent. We have examined the bond between the lactose and a model active pharmaceutical ingredient and possible forming of organised mixtures. We have prepared mixtures of various active pharmaceutical ingredients with lactoses with different content (12.5 % and 25 %) of the active pharmaceutical ingredient. We have used the cone forming method, rotating drum and moving of powders through the sieve to determine the level of segregation. Segregation could not be quantified because there is no measurable unit of segregation. Therefore the result of any measurement is a comparison between different mixtures. Results have shown that mixtures with the modified lactose are at least twice less subjected to segregation than mixtures with commercially available lactoses. Because of the excellent properties of the modified lactose there is a huge potential in its application in the process of direct tableting.
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