Microcrystalline cellulose direct compression diluents

Details of some direct compression diluents are given in Table 6. The majority of these are available from only one supplier, though the two most frequently used—spray-dried lactose and microcrystalline cellulose—are available from several sources. 

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. 

Since its introduction as a direct compression diluent in 1964, microcrystalline cellulose has become a pharmaceutical excipient of great importance. It consists... 

Powdered cellulose has been used as a direct compression diluent. Though it forms hard tablets, fluidity is poor and dilution potential is low. Like microcrystalline cellulose it has some self-lubricating properties, but addition of a lubricant is usually necessary, causing a marked reduction in tablet strength. ... 

Sherwood, B.E. Hunter, E.A. Staniforth, J.N. Silicified microcrystalline cellulose (SMCC ). A new class of high functionality binders for direct compression diluents. 43. Pharm. Res. 1996,13 (9), S197. 

Armstrong, N.A. Lowndes, D.H.L. The use of mixtures of spray-dried lactose and microcrystalline cellulose as direct compression diluents. Int. J. Pharm. Tech, and Prod. Manuf. 1984, 5 (3), 11-14. 

Microcrystalline cellulose (Avicel) is purified partially depolymerized cellulose, prepared by treating a-cellulose with mineral acids. In addition to being used as a filler, it is also used as dry binder and disintegrant in tablet formulations. Depending on the preparation conditions, it can be produced with a variety of technical specifications depending on particle size and crystallinity. It is often used as an excipient in direct compression formulations but can also be incorporated as a diluent for tablets prepared by wet granulation, as a filler for capsules and for the production of spheres. 

At about the same time, two materials were introduced that were specifically designed to act as tablet diluents and would not require preliminary treatment. These were spray-dried lactose and microcrystalline cellulose, introduced in 1962 and 1964, respectively. These two substances can be said to have initiated the direct compression revolution. Since that time, a wide range of direct compression tablet diluents has become available. The properties of some of these materials will be reviewed later in this article. 

Microcrystalline cellulose is widely used in pharmaceuticals, primarily as a binder/diluent in oral tablet and capsule formulations where it is used in both wet-granulation and direct-compression processes.In addition to its use as a binder/diluent, microcrystalline cellulose also has some lubricant and disintegrant properties that make it useful in tableting. 

Owing to the hydrophilic nature of chitosan, this compound has been used directly as compressible diluent in tablets. Chitosan has excellent properties as excipient for direct compression of tablets, where the addition of 50% chitosan results in rapid disintegration. The DD determines the extent of moisture absorption. Also, in immediate-release formulations, e.g., as a disintegrant in small amounts, where it has been found to have effects similar to or better than those of microcrystalline cellulose. Chitosan at concentrations higher than 5% is a better disintegrate than corn starch and microcrystalline cellulose, depending on chitosan crystallinity, DD, MW and particle size [61]. In addition, it has excellent tablet binder properties compared to other excipients [62]. 

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