Oleic acid

• BPOleic Acid
• Ph. Eur.Oleic Acid
• USP–NFOleic Acid

(Z)-9-Octadecenoic acid; cis-9-octadecenoic acid; elaic acid; acidum oleicum; red oil

(Z)-Octadec-9-enoic acid · [112-80-1]

UNII 2UMI9U37CP · PubChem CID 445639

C18H34O2 · 282.47

Penetration enhancer, Surfactant, emulsifier

Typical concentrations: — · Dosage forms: Semi-solid

Used as an emulsifying agent (after partial neutralisation to form soaps) in creams and lotions, as a skin penetration enhancer in topical and transdermal products, as a solubiliser and oily vehicle in oral lipid-based formulations and soft capsules, and as a surfactant or dispersing agent in pressurised metered-dose inhalers.

A yellowish to pale brown, oily liquid with a characteristic lard-like odour and taste. Pharmacopoeial oleic acid is obtained from natural fats and contains other fatty acids besides oleic acid.

Congealing point

about 4–10 °C, depending on grade

Density

≈ 0.89 g/cm³ at 25 °C

Acid value

about 195–204

Iodine value

about 85–95

Solubility

practically insoluble in water; miscible with ethanol (95%), chloroform, ether and fixed and volatile oils

On exposure to air it gradually absorbs oxygen and darkens, developing a rancid odour; antioxidants such as butylated hydroxytoluene or tocopherol may be added. Store in a well-filled, airtight container, protected from light, in a cool place.

Incompatible with aluminium, calcium, heavy metal salts, iodine solutions, perchloric acid and oxidising agents. It reacts with alkalis to form soaps, and its free carboxyl group can react with basic drugs.

Obtained by hydrolysis of animal or vegetable fats and oils (for example tallow or olive oil), followed by separation of the liquid fatty acids from the solid saturated acids and purification by distillation.

A normal dietary component with low oral toxicity. It can irritate the skin at higher concentrations, which is related to its penetration-enhancing effect. Intravenous administration of free oleic acid is harmful (it can cause acute lung injury) and should not occur except as part of approved formulations.

Observe normal precautions for the quantity handled. Eye protection and gloves are recommended; spills are slippery and should be cleaned up promptly.

Permitted in the USA as a food additive under specified conditions (21 CFR 172.860). Included in the FDA Inactive Ingredient Database (inhalation; oral capsules and solutions; topical and transdermal preparations) and in non-parenteral medicines licensed in Europe.

Oleyl alcohol; ethyl oleate; sodium oleate; stearic acid; linoleic acid.

Grades differ in their content of other fatty acids (such as linoleic and palmitic acid) and in peroxide value; low-peroxide, high-purity grades are preferred for inhalation and oxidation-sensitive products.