Sodium carboxymethyl cellulose

Chemical properties

Carboxymethylcellulose sodium occurs as a white to almost white, odorless, tasteless, granular powder. It is hygroscopic after drying.

The Uses of Sodium carboxymethyl cellulose

Sodium carboxymethyl cellulose (CMC) is a food-grade, water-soluble gum used as a thickener, adhesive, emulsifier, flocculant, chelating agent, water-retention agent, sizing agent, and film-forming agent. CMC is also used in drilling muds, dirt suspension agents in detergents, resin latex paints, adhesives, printing inks, textile sizing agents, and as a general protective colloid. It is also used as a stabilizer in foods; in pharmaceuticals as a suspending agent and tablet excipient; as a viscosity modifier to stabilize emulsions; as a lubricant in artificial tears; and for characterizing endoglucanase activity.

Production Methods

Alkali cellulose is prepared by steeping cellulose obtained from wood pulp or cotton fibers in sodium hydroxide solution. The alkaline cellulose is then reacted with sodium monochloroacetate to produce carboxymethylcellulose sodium. Sodium chloride and sodium glycolate are obtained as by-products of this etherification.

brand name

Celluvisc (Allergan); Refresh Plus, Cellufresh Formula (Allergan).

Pharmaceutical Applications

Sodium carboxymethyl cellulose (CMC) is an anionic derivative widely used in oral and topical pharmaceutical formulations. Its aqueous solutions can be used to suspend powders for topical, oral, and parenteral administration. It is also used as a tablet binder and disintegrant, as well as to stabilize emulsions. CMC is also used in self-adhesive ostomy, wound care, and skin patches as a mucoadhesive, absorbing wound exudate or transepidermally absorbing water and sweat. It has also been reported to act as a cytoprotective agent.

Safety

Carboxymethylcellulose sodium is used in oral, topical, and some parenteral formulations. It is also widely used in cosmetics, toiletries, and food products, and is generally regarded as a nontoxic and nonirritant material. However, oral consumption of large amounts of carboxymethylcellulose sodium can have a laxative effect; therapeutically, 4–10 g in daily divided doses of the medium- and high-viscosity grades of carboxymethylcellulose sodium have been used as bulk laxatives.
The WHO has not specified an acceptable daily intake for carboxymethylcellulose sodium as a food additive since the levels necessary to achieve a desired effect were not considered to be a hazard to health. However, in animal studies, subcutaneous administration of carboxymethylcellulose sodium has been found to cause inflammation, and in some cases of repeated injection fibrosarcomas have been found at the site of injection.
Hypersensitivity and anaphylactic reactions have occurred in cattle and horses, which have been attributed to carboxymethylcellulose sodium in parenteral formulations such as vaccines and penicillins.
LD₅₀ (guinea pig, oral): 16 g/kg
LD₅₀ (rat, oral): 27 g/kg

Description

CMC can be used as a binder in the preparation of graphene nano-platelet based inks for the fabrication of dye sensitized solar cells (DSSCs). It can also be used as a viscosity enhancer in the development of tyrosinase based inks for the formation of electrodes for biosensor applications. CMC is used as a support material for a variety of cathodes and anodes for microbial fuel cells.

Storage

Carboxymethylcellulose sodium is a stable, though hygroscopic material. Under high-humidity conditions, carboxymethylcellulose sodium can absorb a large quantity (>50%) of water. In tablets, this has been associated with a decrease in tablet hardness and an increase in disintegration time.
Aqueous solutions are stable at pH 2–10; precipitation can occur below pH 2, and solution viscosity decreases rapidly above pH 10. Generally, solutions exhibit maximum viscosity and stability at pH 7–9.
Carboxymethylcellulose sodium may be sterilized in the dry state by maintaining it at a temperature of 1608℃ for 1 hour. However, this process results in a significant decrease in viscosity and some deterioration in the properties of solutions prepared from the sterilized material.
Aqueous solutions may similarly be sterilized by heating, although this also results in some reduction in viscosity. After autoclaving, viscosity is reduced by about 25%, but this reduction is less marked than for solutions prepared from material sterilized in the dry state. The extent of the reduction is dependent on the molecular weight and degree of substitution; higher molecular weight grades generally undergo a greater percentage reduction in viscosity. Sterilization of solutions by gamma irradiation also results in a reduction in viscosity.
Aqueous solutions stored for prolonged periods should contain an antimicrobial preservative.
The bulk material should be stored in a well-closed container in a cool, dry place.

Purification Methods

Dialyse it for 48hours against distilled water and freeze-dry if a solid is required.

Properties and Applications

TEST ITEMS	SPECIFICATION
	CMC-LV	CMC-HV
Appearance	Cream colored and free flowing powder	Cream colored and free flowing powder
Degree of Substitution	0.6-0.9	0.6-0.9
pH	6-9	6-9
Moisture %	10% max	10% max
Sodium CMC content on dry basis	70% min	70% min
Viscosity at 600RPM	90 max in deionized water 10 max 4% salt water mud,API water loss	30 max in deionized water 30 min in 4% salt water 30 min in 4% saturated salt water 10 max 4% salt water mud,API water loss

Incompatibilities

Carboxymethylcellulose sodium is incompatible with strongly acidic solutions and with the soluble salts of iron and some other metals, such as aluminum, mercury, and zinc. It is also incompatible with xanthan gum. Precipitation may occur at pH < 2, and also when it is mixed with ethanol (95%).
Carboxymethylcellulose sodium forms complex coacervates with gelatin and pectin. It also forms a complex with collagen and is capable of precipitating certain positively charged proteins.

Regulatory Status

GRAS listed. Accepted as a food additive in Europe. Included in the FDA Inactive Ingredients Database (dental preparations; intraarticular, intrabursal, intradermal, intralesional, and intrasynovial injections; oral drops, solutions, suspensions, syrups and tablets; topical preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Nonmedicinal Ingredients.