Ordered mixing, tablets manufacturing

Lubricant The use of a lubricant is essential to increase the free flow of powders and to prevent manufacturing disorders in the tablet production. The type and amount of lubricant are cautiously selected in the formulation. The order of addition and mixing time is also considered in the tableting process. 

Different localized levels of molecular order can coexist in some pharmaceutical materials, giving rise to the occurrence of partially crystalline (and partially amorphous ) systems. In most cases, the properties of such materials (e.g., density) are intermediate to those of the 100% amorphous and 100% crystalline samples. By deliberately varying the level of crystallinity in such systems, their properties can be customized for a particular purpose. An example of this is with the tableting excipients microcrystalline cellulose and spray-dried lactose, which have had their compression characteristics optimized by manipulating their amorphous content. The properties of partially crystalline materials may be approximated in many instances by making physical mixtures of the totally amorphous and crystalline samples. This is known as the two-state model for partially crystalline systems.However, such experiments should be undertaken with caution as the mixed two-state material can sometimes have significantly different properties from the partially crystalline material that is manufactured directly (the real one-state system). ... 

This overview has hardly touched several important topics of current interest pertaining to the mixing of particulate materials and blending of powder. Such topics include the formation of ordered or partially ordered mixtures and prevention of segregation due to percolation in preparing mixtures capable of maintaining specified compositions by various means (see, e.g., [5], [7]). These mixtures are often involved when medicines are produced in the form of pills, tablets, and controlled release devices as well as when advanced materials, e.g., composites and semiconductors, are manufactured. 

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