Carboxymethylcellulose sodium

• BPCarmellose Sodium
• JPCarmellose Sodium
• Ph. Eur.Carmellose Sodium
• USP–NFCarboxymethylcellulose Sodium

Akucell; Aquasorb; Blanose; carmellosum natricum; cellulose gum; CMC sodium; sodium carboxymethylcellulose; Tylose CB; Walocel C; E466

Cellulose, carboxymethyl ether, sodium salt · [9004-32-4]

[C6H7O2(OH)x(OCH2COONa)y]n · ≈ 90 000–700 000

Gelling agent, viscosity modifier, Binder, Disintegrant

Typical concentrations: 1–6% binder · 3–6% gel · Dosage forms: Liquid, Solid, Semi-solid

Widely used in oral, topical and some parenteral formulations, mainly to increase viscosity and as a suspending agent; it is also used as a tablet binder and disintegrant, an emulsion stabiliser and a mucoadhesive, and in wound dressings, cosmetics and foods. Typical concentrations: emulsifying agent 0.25–1.0%; gel-forming agent 3.0–6.0%; injections 0.05–0.75%; oral solutions 0.1–1.0%; tablet binder 1.0–6.0%.

A white to almost white, odourless and tasteless, granular powder. It is hygroscopic after drying.

Degree of substitution

typically 0.7–1.2 carboxymethyl groups per anhydroglucose unit; sodium content 6.5–10.8% (dried substance)

pH

≈ 6.0–8.5 (1% w/v aqueous solution)

pKa

≈ 4.3

Viscosity

grade-dependent; low-, medium- and high-viscosity grades are available, and solutions are pseudoplastic

Moisture content

hygroscopic; typically below 10% w/w as supplied

Solubility

easily dispersed in water at any temperature to form clear colloidal solutions; practically insoluble in acetone, ethanol, ether and toluene

The powder is stable but hygroscopic. Aqueous solutions are stable at pH 2–10; below pH 2 the polymer precipitates and above pH 10 viscosity falls. Heating lowers solution viscosity, and solutions should be preserved against microbial growth. The dry powder can be sterilised by dry heat, and solutions by autoclaving or gamma irradiation, but these processes reduce viscosity. Store in a well-closed container in a cool, dry place.

Incompatible with strongly acidic solutions and with soluble salts of iron and some other metals such as aluminium, mercury and zinc, and with xanthan gum. It is precipitated by ethanol (95%) and forms complex coacervates with gelatin and pectin.

Alkali cellulose, made by treating cellulose from wood pulp or cotton linters with sodium hydroxide, is reacted with sodium monochloroacetate; the product is purified to remove sodium chloride and sodium glycolate.

Regarded as non-toxic and non-irritant after oral and topical use and is not absorbed from the gut; large oral doses act as a bulk laxative. Hypersensitivity reactions, including anaphylaxis, have been reported rarely after injection of products containing it.

Observe normal precautions for the quantity handled. Avoid generating dust; eye protection and gloves are recommended.

GRAS listed. Accepted as a food additive in Europe (E466). Included in the FDA Inactive Ingredient Database (dental preparations; various injections; oral, topical and vaginal preparations) and in parenteral and non-parenteral medicines licensed in Europe.

Carboxymethylcellulose calcium; croscarmellose sodium; microcrystalline cellulose and carboxymethylcellulose sodium.

Viscosity depends strongly on grade, concentration and temperature, so the grade should always be specified. Being an anionic polymer, it may interact with cationic drugs and preservatives; dispersing the powder in a non-solvent such as glycerol before adding water helps to avoid lumps.