Tablet manufacture diluents

Armstrong NA. Tablet manufacture. Diluents. In Swarbrick J, Boylan JC, eds. Encyclopedia of Pharmaceutical Technology, 2nd edn, vol. 3. New York Marcel Dekker, 2002 2713-2732. 

Patel et al. [40] found that moismre and the pH of the micro-environment influenced degradation the most. They identified the best diluent for tablet manufacture as being dibasic calcium phosphate, with a basic modifier (sodium carbonate, sodium bicarbonate or magnesium oxide). The authors indicated that the degradation pathways observed were deiodination, deamination and decarboxylation. The data are shown in Table 2.4. 

Microcrystalline cellulose - mainly used as a binder or diluent in solid oral dose formulations. It also has lubricant and disintegrant properties which make it a useful excipient in tablet manufacture. 

If a major component of the formulation such as the diluent were to possess the necessary degrees of fluidity and compressibility, granulation would be unnecessary. This is the basis of the direct compression method of tablet manufacture. 

A faulty batch of tablets can sometimes be recovered by grinding up the tablets and recompressing them, a process which is known as reworking and is analogous to the dry granulation method of tablet manufacture. This can sometimes cause problems with a direct compression formulation. Many direct compression diluent particles are in the form of aggregates, e.g., spray-dried lactose is composed of small crystals of lactose embedded in amorphous lactose. If these aggregates are compressed, their structure may be broken down to such an extent that subsequent recompression will result in impaired tablet quality. 

Pharmaceutical Applications. Sucrose has a long history in the manufacture of pharmaceuticals. It imparts body to symps and medicinal hquids and masks unpleasant tastes. Sucrose also functions as a diluent to control dmg concentrations in medicines, as an ingredient binder for tablets, and to impart chewiness to the latter. Sustained-release medications and protective tablet glazes are prepared using sucrose (41). Sucrose-based sugar pastes are used to promote wound healing (58). 

The influence of the actual manufacturing process can also affect the contribution of the diluent to the final characteristics of the product. For instance, Shah et al. [45] demonstrated that the release of drug from tablets formulated with soluble excipients may be more... 

Lactose has several applications in food products (Table 2.6), the most important of which is probably in the manufacture of humanized infant formulae. It is used also as a diluent for the tableting of drugs in the pharmaceutical industry (which requires high-quality, expensive lactose) and as the base for plastics. 

Take, for example, dextrose. When dextrose is used as a sweetener in baked goods, it is a food ingredient and subject to the requirements of food products. When dextrose is used as a sweetener or diluent in tablet, capsule, or liquid preparations, it is an excipient. When it is used in the manufacture of sterile dextrose injection, it is an active drug substance and an API but now... 

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. 

Most direct compression diluents are available from only one source, but a few can be obtained from more than one manufacturer. If multiple sources are available, they will be offered under individual registered names. For example, microcrystalline cellulose is available under a number of brand names such as Avicel (FMC Corporation), Emcocel (Edward Mendell), and Vivacel (J. Rettenmaier). Chemical properties of such materials will be similar if not completely identical, especially if there are pharmacopeial standards for identity and purity. However, it cannot be assumed that products from different manufacturers will have the similar physical properties which will govern their performance in the tabletting process. 

Sorbitol can exist in four crystalline forms. Guyot-Hermann, Leblanc, and Draguet-Brugmans compared 11 commercially available varieties of sorbitol, and found three of these four forms to be present. y-Sorbitol was found to be the most useful as a tablet diluent. The method of manufacture has also been shown to affect tabletting properties, differences being attributed to variations in particle shape and surface properties. Spray-dried varieties of sorbitol are available as direct compression diluents which are claimed to have overcome problems associated with the different crystalline forms. ... 

USE Both forms of lactose are employed, with the a-form predominating as a nutrient in preparing modified milk and food for infants and convalescents (Whittier, "Lactose and Its Utilization. foe. cit review with 327 ref). In baking mixtures. Pharmaceutic aid (tablet and capsule diluent). To produce lactic acid fermentation in ensilage and food products. As chromatographic adsorbent in analytical chemistry. In culture media. For many other uses see the comprehensive review by Weisberg Recent Progress in the Manufacture and Use of Lactose, toe. cit. 

Dicalcium phosphate (anhydrous or sometimes as the dihydrate) has many uses. These include glass manufacture, plastics stabilisation, fertilisers and animal feeds. In addition, it is used as a dough additive, a nutrient and a dietary supplement. In pharmacy, it is used as a tablet diluent and dispersant calcium phosphates have other medical applications [32]. Other uses include paint and pigments and in toothpaste as a secondary abrasive. 

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