Microcrystalline cellulose, function

The lambda type is nongelling, and functions as a thickner. Iota-carrageenan has been recommended (45) for use in formulating low fat ground beef due to its abihty to retain moisture, especially through a freeze—thaw cycle which is typical for ground beef patties. Oat bran and oat fiber can also be used to improve moisture retention and mouth feel. Modified starches can be used as binders to maintain juiciness and tenderness in low fat meat products. Maltodextrins (dextrose equivalent less than 20) may be used as binders up to 3.5% in finished meat products. Other carbohydrates such as konjac flour, alginate, microcrystalline cellulose, methylceUulose, and carboxymethylceUulose have also been used in low fat meat products (see CELLULOSE ETHERs). 

The sorption of water by excipients derived from cellulose and starch has been considered by numerous workers, with at least three thermodynamic states having been identified [82]. Water may be directly and tightly bound at a 1 1 stoichiometry per anhydroglucose unit, unrestricted water having properties almost equivalent to bulk water, or water having properties intermediate between these two extremes. The water sorption characteristics of potato starch and microcrystalline cellulose have been determined, and comparison of these is found in Fig. 11. While starch freely adsorbs water at essentially all relative humidity values, microcrystalline cellulose only does so at elevated humidity values. These trends have been interpreted in terms of the degree of available cellulosic hydroxy groups on the surfaces, and as a function of the amount of amorphous material present [83]. 

Although its two domains could function independently, removal of the substrate-binding domain of ngCenA reduced enzymatic activity against microcrystalline cellulose but not against CMC or amorphous cellulose (12). This suggested that the substrate-binding domain played a critical role in the hydrolysis of crystalline cellulose. 

Sherwood BE, Becker JW. A new class of high functionality excipients silicified microcrystalline cellulose. Pharm Tech 1998 22(10) 78—88. 

Staniforth JN, Chatrath M. Towards a new class of high functionality tablet binders. I Quasi-hornification of microcrystalline cellulose and loss of functionality. Pharm Res 1996 13 S208. 

However, some excipients have multiple functions. For example, microcrystalline cellulose can function as a filler, a binder, and a disintegrant. As seen in Table 7.3, a typical low-dose formulation could include more than 85% filler—binders. Thus, physical and chemical properties for these specialty excipients are extremely important in a low-dose formulation for manufacturability, product performance, and longterm stability. Because the poor physicomechanical properties of components are not altered during manufacture as they are in the wet or dry granulation process, critical material properties and their impact on product quality attributes should be well characterized and understood.23 Discussion in this section will focus on fillers-binders. For those requiring more information on excipients, several excellent books and review articles are available in the literature.24-27... 

Figure 8 also shows an example of moisture uptake for four selected excipients as a function of relative humidity. Depending on the hygroscopicity of the exscipi-ents, the uptake behaviors are quite variable. Excipients such as microcrystalline cellulose (MCC) and starch can pick up significant amounts of water at relatively low relative humidity. Since this water is not present as a hydrate, it is potentially free to interact with a drug. 

Fig. 3 Steady-state extrusion force as a function of the length-to-radius ratio of the die for microcrystalline cellulose-lactose-water (5 5 6) at constant die diameter (1.5 mm) and extrusion rate (20cm/min).

Gohel, M.C. Patel, L.D. Modi, C.J. Jogani, P.D. Functionality testing of a coprocessed diluent containing lactose and microcrystalline cellulose. Pharm. Technol. 1999, 44-46, Yearbook. 

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. 

Wu JS, Ho HO, Sheu MT. A statistical design to evaluate the influence of manufacturing factors on the material properties and functionalities of microcrystalline cellulose. Eur ] Pharm Sci 2001 12 417 25. 

Tobyn MJ, Staniforth JN, Hunter EA. Compaction studies on a new class of high functionality binders silicified microcrystalline cellulose (SMCC). Pharm Res 1996 13(9) S198. 

The resolution of optical antipodes on polysaccharides is mainly governed by the shape and size of solutes (inclusion phenomena) and only to a minor extent by other interactions involving the functional groups of the molecules. In the case of microcrystalline cellulose triacetate (MCTA), the type and composition of the aqueous-organic eluent affect the separation because these result in different swelling of MCTA. 

Most systems function with paste but Young et al. (10) described the use of a process whereby the extrusion was with a hot-melt system, the extrudate cut in a pelletizer (Randcastle RCP-2,0, Randcastle Inc. Cedar Grove. New Jersey, U.S.A.) into cylindrical pellets, which were then spheronized on a conventional spheronizer (Caleva Model 120, AC Compacting LLc, North Brunswick, New Jersey, U.S.A.) heated with a heat gun to 65-70 C while dusting with microcrystalline cellulose (MCC) to prevent agglomeration. The picture of the pellets shown to illustrate the product appears round but the process times of 45 and 80 minutes are considerably longer than those involved with the paste systems. 

Figure 3 Tensile strength of tablets formed from microcrystalline cellulose as a function of relative density. In agreement with percolation theory, a power-law behavior was observed close to the percolation threshold solid line), and a crossover to an effective-medium behavior was seen for larger relative density dashed line). Source From Ref. 20.

Produced from renewable resources, organic fibers and their derivatives have a wide range of functional applications. In the pharmaceutical and food industries, the presently best known cellulosic additive is microcrystalline cellulose (MCC). It is obtained from wood cellulose by acidic hydrolysis. The product does no longer contain lignins, hemicelluloses, or other impurities and is bleached to produce a high degree of brightness. 

Native and microcrystalline cellulose precoated plates are used in the life sciences for the separation of polar compounds (e.g. carbohydrates, carboxylic acids, amino acids, nucleic acid derivatives, phosphates, etc) [85]. These layers are unsuitable for the separation of compounds of low water solubility unless first modified, for example, by acetylation. Several chemically bonded layers have been described for the separation of enantiomers (section 10.5.3). Polyamide and polymeric ion-exchange resins are available in a low performance grade only for the preparation of laboratory-made layers [82]. Polyamide layers are useful for the reversed-phase separation and qualitative analysis of phenols, amino acid derivatives, heterocyclic nitrogen compounds, and carboxylic and sulfonic acids. Ion-exchange layers prepared from poly(ethyleneimine), functionalized poly(styrene-divinylbenzene) and diethylaminoethyl cellulose resins and powders and are used primarily for the separation of inorganic ions and biopolymers. 

Phosphorylation of microcrystalline cellulose under the action of microwave irradiation was achieved by Gospodinova et al. [83]. The reactions were performed in a single-mode microwave reactor under an argon atmosphere. Mixtures of 29.0 mmol urea, 17.6 mmol phosphorous acid, and 1.8 mmol cellulose were irradiated for 60 to 120 min at temperatures from 75 to 150 °C (Scheme 14.42). The process led to monosubstituted phosphorous acid esters of cellulose with different degrees of substitution of hydroxy functions (0.2 to 2.8) without pretreatment with solvents. 

Fig. 21. Remission function for benzophenone adsorbed on microcrystalline cellulose.

Fig. 25. Diffuse reflectance spectra for TCC and 9-MeTCC adsorbed on microcrystalline cellulose as a function of the dye concentration.

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