Calcium alginate

• BPCalcium Alginate

Alginic acid, calcium salt; calcium polymannuronate; E404

Calcium alginate · [9005-35-0]

(C12H14CaO12)n

Gelling agent, viscosity modifier, Disintegrant

Typical concentrations: — · Dosage forms: Solid

Used as a tablet disintegrant, as a thickening, gelling and stabilising agent, and in controlled-release systems such as calcium-crosslinked alginate beads and microcapsules. Fibres of calcium alginate are widely used in absorbent, haemostatic wound dressings. It is also used in foods.

A white to pale yellowish-brown, almost odourless and tasteless powder or fibrous material.

Solubility

practically insoluble in water, ethanol and other organic solvents; dissolves in solutions of substances that bind calcium, such as sodium citrate

Composition

calcium salt of a linear copolymer of β-D-mannuronic acid and α-L-guluronic acid; the M/G ratio depends on the seaweed source

Behaviour in sodium-containing fluids

exchanges calcium for sodium ions to form a soft, hydrophilic gel

Stable when kept dry. Store in a well-closed container in a cool, dry place.

Calcium-sequestering agents such as citrates, phosphates and edetate break down the calcium crosslinks and dissolve or weaken the gel. Incompatible with strong oxidising agents.

Alginic acid is extracted from brown seaweeds (Phaeophyceae) with dilute alkali, and calcium alginate is precipitated by adding a soluble calcium salt such as calcium chloride to a sodium alginate solution. Fibres are made by extruding sodium alginate solution into a calcium chloride bath.

Generally regarded as non-toxic and non-irritant. Alginate wound dressings are well tolerated, and alginates are widely consumed in foods.

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

GRAS listed. Accepted as a food additive in Europe (E404).

Alginic acid; potassium alginate; propylene glycol alginate; sodium alginate.

Gels rich in guluronic acid (high G) bind calcium more strongly and are firmer and more brittle than mannuronic-rich gels. In wound dressings the ion exchange with sodium in exudate turns the fibres into a moist gel that can be removed with little trauma.