Granules compression properties

The true direct compression process as described earlier almost invariably applies to formulations containing potent active ingredients and where the direct compression properties derive from the diluent. A few substances do possess adequate flow and cohesive properties without the need for pretreatment. These are usually crystalline inorganic salts such as sodium chloride and potassium chloride. Direct compression forms of less potent active ingredients are available e.g., paracetamol and ascorbic acid. These can be directly compressed into tablets, perhaps after the addition of a lubricant. However, such substances are more accurately described as pre-granulated, in that the granulation process—either wet granulation or precompression—has been carried out by the excipient manufacturer. 

Multivariate optimization of wet granulation may include hardness, disintegration, and ejection as response variables. Compressibility property of... 

Powder fills for capsules can be either simple blends of starting materials, analogous to direct compression formulations, or granulations. The reduced demands on compressibility and flow increase the options for powder mixes, making capsules a potential dosage form for active substances that do not possess the compression properties required for direct compression tablets and are not amenable to granulation. 

The objective was to obtain tablets of low friability and satisfactory hardness. Good compression properties were also needed, that is a high transmission ratio and also a high cohesion index (see below). A granulate with at least 20% fine particles was also considered desirable, for the powder to flow correctly. 

The compressional behavior of four polymorphs of mannitol (the a, P, and 5 forms, as well as one unidentified phase) has been studied [57]. It was found that the compressibility of the a-phase is superior, and fortunately this phase is the major form in most commercial products. The particle shape was found to exert an influence upon the compressibility properties granulated powders show better behavior than native crystalline powders. It was reported that no polymorphic transitions took place under the compression stresses used during the tableting process. 

The PDG process can granulate virtually any pharmaceutical solid dosage ingredient. The granulated material has exceptionally good flowability and compressibility properties. 

During the preformulation stage, the chemical and physical properties of the dmg moiety are studied exhaustively to ensure stabdity, safety, bioavadabdity, and therapeutic efficacy. Tablets are produced directly by compression of powder blends or granulations, which include a small percentage of fine, particle-sized powders. 

Direct Compression. This process is relatively simple and time saving. AH the ingredients are blended and then compressed into the final tablet. This is an excellent method, but encumbered by a number of problems. Not all substances can be compressed directly, necessitating a granulation step. Likewise, the flow properties of many blends of fine, particle-sized powders are not such as to ensure even filling of the die cavities of tablet presses. In addition, air entrapment can occur. 

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