Chemical Properties
yellow wax
Characteristics
Lanolin is a waxy substance that sheep naturally produce to protect their wool. Because lanolin's properties are similar to those of the sebum (oil) secreted by human skin, it is a popular ingredient in moisturizers, hair care products, and soaps.
Definition
A yellowish viscous
substance obtained from wool fat. It contains
cholesterol and terpene compounds,
and is used in cosmetics, in ointments, and
in treating leather.
Definition
lanolin: An emulsion of purified wool fat in water, containing cholesteroland certain terpene alcoholsand esters. It is used in cosmetics.
Production Methods
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.
Pharmaceutical 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.
Side effects
Most emollients can be used safely and effectively without side effects. However, burning, stinging, redness or irritation may occur. Rare and very serious allergic reactions are abnormal changes in the skin (e.g., whitening/softening/wetness from over-moisturisation), rashes, itching/swelling (especially on the face/tongue/throat), severe dizziness, and difficulty breathing. If any discomfort occurs, contact your doctor immediately.
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.
storage
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°C. Ophthalmic ointments containing lanolin
may be sterilized by filtration or by exposure to gamma irradiation.
Incompatibilities
Lanolin may contain prooxidants, which may affect the stability of
certain active drugs.
Regulatory Status
Included in the FDA Inactive Ingredients Database (ophthalmic,
otic, topical, and vaginal preparations). Included in nonparenteral
medicines licensed in the UK. Included in the Canadian List of
Acceptable Non-medicinal Ingredients.
