Glyceryl monostearate

Definition

An intermediate chemical.

Production Methods

Glyceryl monostearate is prepared by the reaction of glycerin with triglycerides from animal or vegetable sources, producing a mixture of monoglycerides and diglycerides. The diglycerides may be further reacted to produce the 90% monoglyceride grade. Another process involves reaction of glycerol with stearoyl chloride. The starting materials are not pure substances and therefore the products obtained from the processes contain a mixture of esters, including palmitate and oleate. Consequently, the composition, and therefore the physical properties, of glyceryl monostearate may vary considerably depending on the manufacturer.

Pharmaceutical Applications

The many varieties of glyceryl monostearate are used as nonionic emulsifiers, stabilizers, emollients, and plasticizers in a variety of food, pharmaceutical, and cosmetic applications. It acts as an effective stabilizer, that is, as a mutual solvent for polar and nonpolar compounds that may form water-in-oil or oil-in-water emulsions.These properties also make it useful as a dispersing agent for pigments in oils or solids in fats, or as a solvent for phospholipids, such as lecithin. Glyceryl monostearate has also been used in a novel fluidized hot-melt granulation technique for the production of granules and tablets. Glyceryl monostearate is a lubricant for tablet manufacturing and may be used to form sustained-release matrices for solid dosage forms. Sustained-release applications include the formulation of pellets for tablets or suppositories, and the preparation of a veterinary bolus. Glyceryl monostearate has also been used as a matrix ingredient for a biodegradable, implantable, controlledrelease dosage form. When using glyceryl monostearate in a formulation, the possibility of polymorph formation should be considered. The aform is dispersible and foamy, useful as an emulsifying agent or preservative. The denser, more stable, b-form is suitable for wax matrices. This application has been used to mask the flavor of clarithromycin in a pediatric formulation.

Safety Profile

Poison by intraperitoneal route. When heated to decomposition it emits acrid smoke and irritating fumes. See also ESTERS.

Safety

Glyceryl monostearate is widely used in cosmetics, foods, and oral and topical pharmaceutical formulations, and is generally regarded as a nontoxic and nonirritant material. LD50 (mouse, IP): 0.2 g/kg

storage

If stored at warm temperatures, glyceryl monostearate increases in acid value upon aging owing to the saponification of the ester with trace amounts of water. Effective antioxidants may be added, such as butylated hydroxytoluene and propyl gallate. Glyceryl monostearate should be stored in a tightly closed container in a cool, dry place, and protected from light.

Incompatibilities

The self-emulsifying grades of glyceryl monostearate are incompatible with acidic substances.

Regulatory Status

GRAS listed. Included in the FDA Inactive Ingredients Database (oral capsules and tablets; ophthalmic, otic, rectal, topical, transdermal, and vaginal preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients. If glyceryl monostearate is produced from animal fats (tallow), there may be additional regulatory requirements that the source be free of contamination from bovine spongiform encephalopathy.