Aluminum monostearate

• USP–NFAluminum Monostearate

Aluminium monostearate; aluminium hydroxide stearate; dihydroxy(octadecanoato)aluminium; aluminum stearate (mono)

Dihydroxy(octadecanoato-O)aluminium · [7047-84-9]

UNII P9BC99461E · PubChem CID 10246924

C18H37AlO4 · 344.47

Gelling agent, viscosity modifier

Typical concentrations: — · Dosage forms: Semi-solid

Used as a gelling and thickening agent for oils, notably to give thixotropic, slowly dispersing oily vehicles for depot intramuscular suspensions, and as a stabiliser and thickener in ointments, creams and cosmetics. It also acts as a water-repellent and emulsion stabiliser.

A fine, white to yellowish-white, bulky powder with a faint, characteristic odour. It is a compound of aluminium with a mixture of solid organic acids from fats, mainly stearic and palmitic acids.

Composition

aluminium compound of stearic and palmitic acids, consisting mainly of the monostearate

Solubility

practically insoluble in water, ethanol and ether; forms gels when heated with fixed oils or aromatic hydrocarbons

Appearance

fine, bulky white to yellowish-white powder

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

Incompatible with strong acids, which liberate the fatty acids, and with strong oxidising agents.

Prepared by reacting a soluble aluminium salt with sodium stearate (or a sodium soap of mixed stearic and palmitic acids) in aqueous solution under controlled conditions, followed by washing and drying of the precipitate.

Regarded as of low toxicity and non-irritant at the levels used in topical and depot preparations. As with other aluminium compounds, the total aluminium load should be considered in products for patients with renal impairment.

Observe normal precautions for the quantity handled. Avoid dust formation; eye protection and a dust mask are recommended.

Included in the USP–NF. Used in topical preparations and in oily intramuscular depot suspensions.

Aluminium distearate; aluminium tristearate; calcium stearate; magnesium stearate; zinc stearate.

To form an oil gel the powder is dispersed in the oil and heated (typically above about 120 °C) until it dissolves, then cooled; the final viscosity depends strongly on heating temperature, time and cooling rate, so these must be standardised.