Lanolin

Category

Emulsifying Agents; Ointment Base

Molecular Weight

/

Grade

Pharmceutical Excipients

Description

Lanolin is a pale yellow-colored, unctuous, waxy substance with a faint, characteristic odor. Melted lanolin is a clear or almost clear, yellow liquid.

UNII

7EV65EAW6H

Chemical Name

Anhydrous lanolin

CAS Number

8006-54-0

Synonyms

Adeps lanae; cera lanae; E913; lanolina; lanolin anhydrous; Protalan anhydrous; purified lanolin; refined wool fat

Administration route

Ophthalmic, otic, topical, and vaginal

Dosage Form

Ophthalmic, otic, topical, and vaginal preparations

Stability and Storage Conditions

Lanolin may gradually undergo autoxidation during storage. To inhibit this process, the inclusion of butylated hydroxytoluene is permitted as an antioxidant. Exposure to excessive or prolonged heating may cause anhydrous lanolin to darken in color and develop a strong rancidlike odor. However, lanolin may be sterilized by dry heat at 150℃. Ophthalmic ointments containing lanolin may be sterilized by filtration or by exposure to gamma irradiation. Lanolin should be stored in a well-filled, well-closed container protected from light, in a cool, dry place. Normal storage life is 2 years.

Source and Preparation

Lanolin is a naturally occurring wax-like material obtained from the wool of sheep, Ovis aries Linne´ (Fam. Bovidae). Crude lanolin is saponified with a weak alkali and the resultant saponified fat emulsion is centrifuged to remove the aqueous phase.The aqueous phase contains a soap solution from which, on standing, a layer of partially purified lanolin separates. This material is then further refined by treatment with calcium chloride, followed by fusion with unslaked lime to dehydrate the lanolin. The lanolin is finally extracted with acetone and the solvent is removed by distillation.

Applications

Lanolin is widely used in topical pharmaceutical formulations and cosmetics. Lanolin may be used as a hydrophobic vehicle and in the preparation of water-in-oil creams and ointments. When mixed with suitable vegetable oils or with soft paraffin, it produces emollient creams that penetrate the skin and hence facilitate the absorption of drugs. Lanolin mixes with about twice its own weight of water, without separation, to produce stable emulsions that do not readily become rancid on storage.

Safety

Lanolin is widely used in cosmetics and a variety of topical pharmaceutical formulations. Although generally regarded as a nontoxic and nonirritant material, lanolin and lanolin derivatives are associated with skin hypersensitivity reactions, and the use of lanolin in subjects with known sensitivity should be avoided.Other reports suggest that ‘sensitivity’ arises from false positives in patch testing. However, skin hypersensitivity is relatively uncommon; the incidence of hypersensitivity to lanolin in the general population is estimated to be around 5 per million. Sensitivity is thought to be associated with the content of free fatty alcohols present in lanolin products rather than the total alcohol content.The safety of pesticide residues in lanolin products has also been of concern.However, highly refined ‘hypoallergenic’ grades of lanolin and grades with low pesticide residues are commercially available.

Incompatibilities

Lanolin may contain prooxidants, which may affect the stability of certain active drugs.