Methylcellulose properties

Campbell JM, Fahey GC. Psylium and methylcellulose properties in relation to insoluble and soluble fiber standards. Nutr Res 1997 17 619-629. 

Hydroxypropyl methylcellulose phthalate Synonyms HPMCP Hypromellose phthalate Definition A monophthalic acid ester of hydroxypropyl methylcellulose Properties Wh. powd., odorless, tasteless pract. insol. in water... 

A cement slurry additive consisting of methylcellulose, melamine-formaldehyde resin, and trioxane has been proposed for better bonding of cement to the casing string [20]. Bisphenol-A epoxide resins, with amine-based curing agents, sand filler, and a mixture of n-butanol and dimethyl benzene as a diluent, have been proposed as additives to increase adhesion properties of cement [572]. 

The properties of hydroxyethylcellulose are like those of methylcellulose except for the fact that there is little or no temperature effect on solubility. The degree of substitution required to impart water solubility will depend both upon the degree of polymerization of the cellulose and upon the uniformity of substitution. It is of interest... 

Although vehicle control animals are not required for commonly used vehicles (water, oil, methylcellulose), most regulations require that the biological properties of a vehicle be known and/or that historical data be available. Unfortunately, the best solvents are generally toxic and, thus, cannot be used as vehicles. Ethanol and acetone can be tolerated in relatively high doses but produce effects that may complicate interpretation of toxicity associated with the test material alone. It is sometimes possible to dissolve a material in a small amount of one of these vehicles and then dilute the solution in water or in oil. 

Most peptides and proteins are water-soluble, and therefore D-PBS or saline can be used as a vehicle. Often, however, limited information is available about the solubility properties of novel small molecules, and the choice of a non-toxic vehicle is more difficult. For example, 200 pi of a 5% ethanol solution is equivalent to one beer in humans and may affect behavior. A solution of 20% cyclodextrin has no known side effects in vivo, but in rare cases, some compounds are trapped in the solution and therefore mice have no exposure to the compound. Some vehicles used for in vitro studies can be toxic in live mice. Some vehicles such as methylcellulose have no side effect when given p.o., but are toxic if administered i.v. Access to information about the pharmacokinetics properties of a test compound can help in the choice of a vehicle. 

A radiotelemetric method has been described to test the disintegration property of a tablet [58], A tablet containing a citrate buffer was coated with hydroxypropyl methylcellulose phthalate and then placed in a Heidelberg capsule that also contained a pH-electrode (Figure 8). An antenna is strapped around the midriff of the dog to detect the output from the Heidelberg capsule. 

A large number of macromolecules possess a pronounced amphiphilicity in every repeat unit. Typical examples are synthetic polymers like poly(l-vinylimidazole), poly(JV-isopropylacrylamide), poly(2-ethyl acrylic acid), poly(styrene sulfonate), poly(4-vinylpyridine), methylcellulose, etc. Some of them are shown in Fig. 23. In each repeat unit of such polymers there are hydrophilic (polar) and hydrophobic (nonpolar) atomic groups, which have different affinity to water or other polar solvents. Also, many of the important biopolymers (proteins, polysaccharides, phospholipids) are typical amphiphiles. Moreover, among the synthetic polymers, polyamphiphiles are very close to biological macromolecules in nature and behavior. In principle, they may provide useful analogs of proteins and are important for modeling some fundamental properties and sophisticated functions of biopolymers such as protein folding and enzymatic activity. 

The absorptive properties of commonly used powders such as titanium dioxide (TiC>2), zinc oxide (ZnO), kaolin, cornstarch, and methylcellulose were shown to differ considerably when evaluated under standardized conditions (Figure 22.2). The highest water absorption was shown with ZnO and kaolin, followed by cornstarch and Ti02. Methylcellulose formed a gel with water that prevented the entire soaking of the powder, and thus water absorption remained low. 

Sarkar, N. (1979). Thermal gelation properties of methyl and hydroxypropyl methylcellulose. /. Appl. Polym. Sci. 24 1073-1087. 

A popular approach to improve ocular drag bioavailability is to incorporate soluble polymers into an aqueous solution to extend the drug residence time in the cul-de-sac. It is reasoned that the solution viscosity would be increased and hence solution drainage would be reduced. The more commonly used viscolyzing agents include PVA and derivatives of cellulose. Cellulosic polymers, such as methylcellulose, hydroxyethylcellulose (HEC), hydroxypropyl-methylcellulose (HPMC) and hydroxypropylcellulose (HPC), are widely used as viscolyzers showing Newtonian properties. They have common properties ... 

In general, these groups of cellulose ethers have been used for their innate adhesive properties and to provide thickening to adhesive formulations. They are used for plywood adhesives, industrial adhesives, wallpaper paste, library paste, and latex adhesives. For example, methylcellulose is used in some adhesives as an additive to control viscosity, especially in the heat-cure phenol-formaldehyde glues and other hot-pressing adhesives. Hydroxyethylcellulose is used as an ingredient in polyvinyl acetate emulsions, where it acts as a thickener and protective colloid. 

Combining thermal- with pH-dependent gelation, Kumar et al. [86] developed a combination of methylcellulose 15% and carbopol 0.3%. This composition exhibited a sol-to-gel transition between 25 and 37 °C with a pH increase from 4 to 7.4 [203], A possible mechanism for the thermal effect could be the decrease in the degree of the methylcellulose hydration, while the polyacrylic acid can transform into a gel upon an increase in pH due to the buffering properties of the tear fluid [1]. 

Substituted Cellulose Ethers. Since their introduction for ophthalmic use, MC and other substituted cellulose ethers such as hydroxyethylcellulose, hydroxypropylcel-lulose, hydroxypropyl methylcellulose (HPMC), and carboxymethylcellulose (CMC) have been used in artificial tear formulations.These colloids dissolve in water to produce colorless solutions of varying viscosity. They have the proper optical clarity, a refractive index similar to the cornea, and are nearly inert chemically. Their relative lack of toxicity, their viscous properties, and their beneficial effects on tear film stability have made cellulose ethers useful components of artificial tear preparations. Historically, the most frequently used representative of this group was MC. 

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