Alginic Acid

Category

Stabilizing Agents; Suspending Agents; Sustained Release Agents; Tablet Binder; Tablet Dsintegrant; Viscosity-increasing Agents

Molecular Formula

(C6H8O)n

Molecular Weight

20000 ~ 240000

Grade

Pharmceutical Excipients

Description

Alginic acid is a tasteless, practically odorless, white to yellowish white, fibrous powder.

UNII

8C3Z4148WZ

Chemical Name

Alginic acid

CAS Number

9005-32-7

Synonyms

Acidum alginicum; E400; Kelacid; L-gulo-D-mannoglycuronan; polymannuronic acid; Protacid; Satialgine H8

Administration route

Ophthalmic, oral

Dosage Form

Ophthalmic preparations, oral capsules, and tablets

Stability and Storage Conditions

Alginic acid hydrolyzes slowly at warm temperatures producing a material with a lower molecular weight and lower dispersion viscosity.Alginic acid dispersions are susceptible to microbial spoilage on storage, which may result in some depolymerization and hence a decrease in viscosity. Dispersions should therefore be preserved with an antimicrobial preservative such as benzoic acid; potassium sorbate; sodium benzoate; sorbic acid; or paraben. Concentrations of 0.1-0.2% are usually used. Alginic acid dispersions may be sterilized by autoclaving or filtration through a 0.22 mm filter. Autoclaving may result in a decrease in viscosity which can vary depending upon the nature of any other substances present. Alginic acid should be stored in a well-closed container in a cool, dry place.

Source and Preparation

Alginic acid is a hydrophilic colloid carbohydrate that occurs naturally in the cell walls and intercellular spaces of various species of brown seaweed (Phaeophyceae). The seaweed occurs widely throughout the world and is harvested, crushed, and treated with dilute alkali to extract the alginic acid.

Applications

Alginic acid is used in a variety of oral and topical pharmaceutical formulations. In tablet and capsule formulations, alginic acid is used as both a binder and disintegrating agent at concentrations of 1-5% w/w. Alginic acid is widely used as a thickening and suspending agent in a variety of pastes, creams, and gels; and as a stabilizing agent for oil-in-water emulsions. Alginic acid has been used to improve the stability of levosimendan.Therapeutically, alginic acid has been used as an antacid.In combination with an H2-receptor antagonist, it has also been utilized for the management of gastroesophageal reflux.

Safety

Alginic acid is widely used in food products and topical and oral pharmaceutical formulations. It is generally regarded as a nontoxic and nonirritant material, although excessive oral consumption may be harmful. Inhalation of alginate dust may be an irritant and has been associated with industrially related asthma in workers involved in alginate production. However, it appears that the cases of asthma were linked to exposure to unprocessed seaweed dust rather than pure alginate dust. An acceptable daily intake of alginic acid and its ammonium, calcium, potassium, and sodium salts was not set by the WHO because the quantities used, and the background levels in food, did not represent a hazard to health. LD50 (rat, IP): 1.6 g/kg

Incompatibilities

Incompatible with strong oxidizing agents; alginic acid forms insoluble salts in the presence of alkaline earth metals and group III metals with the exception of magnesium.