Nonproprietary Names

None adopted.

Synonyms

Alginic acid, ammonium salt; ammonium polymannuronate; E404; Keltose.

Chemical Name and CAS Registry Number

Ammonium alginate [9005-34-9]

Empirical Formula and Molecular Weight

(C6H11NO6)n 193.16 (calculated) 217 (actual, average) Ammonium alginate is the ammonium salt of alginic acid.

Structural Formula

The number and sequence of the mannuronate and glucuronate residues shown above vary in the naturally occurring alginate. The associated water molecules are not shown.

Functional Category

Diluent; emulsifying agent; film-forming agent; humectant; stabilizing agent; thickening agent.

Applications in Pharmaceutical Formulation or Technology

Technology Ammonium alginate is widely used in foods as a stabilizer, thickener and emulsifier. It is also used in pharmaceutical preparations as a color-diluent, emulsifier, film-former, and humectant.

Description

Ammonium alginate occurs as white to yellowish brown filamentous, grainy, granular, or powdered forms.

Pharmacopeial Specifications

See Section 18.

Typical Properties

Moisture content Not more than 15% at 1058C for 4 hours. Solubility Dissolves slowly in water to form a viscous solution; insoluble in ethanol and in ether.

Stability and Storage Conditions

Ammonium alginate is a hygroscopic material, although it is stable if stored at low relative humidities and cool temperatures.

Incompatibilities

Incompatible with oxidizing agents and strong acids and alkalis.

Method of Manufacture

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Safety

Ammonium alginate is widely used in cosmetics and food products, and also in pharmaceutical formulations such as tablets. It is generally regarded as a nontoxic and nonirritant material, although excessive oral consumption may be harmful.

Handling Precautions

Observe normal precautions appropriate to the circumstances and quantity of the material handled. Eye protection, gloves, and a dust respirator are recommended.

Regulatory Status

GRAS listed. Accepted in Europe for use as a food additive. Included in the FDA Inactive Ingredients Database (oral, tablets). 17 Related Substances Alginic acid; calcium alginate; potassium alginate; propylene glycol alginate; sodium alginate.

Comments

Alginates are commonly used in wound dressings.(1) Chitosan and alginates have been used together to produce sponges for use as wound dressings, or matrices for tissue engineering.(2) Alginate microspheres have been produced by internal gelation using emulsification methods.(3) Although not included in any pharmacopeias, a specification for ammonium alginate is contained in the Food Chemicals Codex (FCC), see Table I. Table I: FCC specification for ammonium alginate.(4) Test FCC 6(4) Identification Arsenic þ43 mg/kg Ash 47.0% after drying Lead 45 mg/kg Loss on drying 415.0% Assay 18.0–21.0% of CO2, corresponding to 88.7–103.6% ammonium alginate 19 Specific References 1 Morgan D. Wounds—what should a dressing formulary include? Hosp Pharm 2002; 9(9): 261–266. 2 Lai HL et al. The preparation and characterization of drug-loaded alginate and chitosan sponges. Int J Pharm 2003; 251(1–2): 175–181. 3 Chan LWet al. Production of alginate microspheres by internal gelation using an emulsification method. Int J Pharm 2002; 242(1–2): 259–262. 4 Food Chemicals Codex, 6th edn. Bethesda, MD: United States Pharmacopeia, 2008; 44.

General References

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Author

s SA Shah, D Thassu.

Date of Revision

30 June 2008.