Polyethylene Glycol

Absorption

PEGs can be absorbed by the gastrointestinal tract following oral administration with the fraction absorbed being dependent on the molecular weight of the compound . It is likely to display minimal absorption through the intact skin, but may penetrate through injured skin with compromised barrier function .

Toxicity

PEG of different molecular weights by a range of routes has been studied extensively, and has not led to any major toxicities, and signs/symptoms of toxicity that do occur are only observed at a much higher than therapeutic dose .
LD50 = 157000 mg/kg, intragastric, guinea pigs LD50 = 28915 mg/kg, intragastric, mice, rats LD50 = 9708 mg/kg, intra-abdominal, rats LD50= 7312 mg/kg, intravenous, rats

Description

Polyethylene glycols are a family of linear polymers formed by a base-catalyzed condensation reaction with repeating ethylene oxide units being added to ethylene. The molecular formula is (C2H4O)multH2O where mult denotes the average number of oxyethylene groups. The molecular weight can range from 200 to several million corresponding to the number of oxyethylene groups. The higher-molecular-weight materials (100 000 to 5 000 000) are also referred to as polyethylene oxides. The average molecular weight of any specific polyethylene glycol product falls within quite narrow limits (°5%). The number of ethylene oxide units or their approximate molecular weight (e.g., PEG-4 or PEG-200) commonly designates the nomenclature of specific polyethylene glycols. Polyethylene glycols with amolecular weight less than 600 are liquid, whereas those of molecular weight 1000 and above are solid. These materials are nonvolatile, water-soluble, tasteless, and odorless. They are miscible with water, alcohols, esters, ketones, aromatic solvents, and chlorinated hydrocarbons, but immiscible with alkanes, paraffins, waxes, and ethers.

The Uses of Polyethylene Glycol

Used in conjunction with carbon black to form a conductive composite.1 Polymer nanospheres of poly(ethylene glycol) were used for drug delivery.2

Indications

Indicated as a lubricant in over-the-counter ophthalmic solutions to temporarily relieve redness, burning and irritation of the eyes.

Background

Polyethylene glycols (PEGs) are products made of condensed ethylene oxide and water that can contain various derivatives and have various functions. Because many PEG types are hydrophilic, they are favorably used as enhancers of penetration, and used heavily in topical dermatological preparations. PEGs, along with their many nonionic derivatives, are widely utilized in cosmetic products as surfactants, emulsifiers, cleansing agents, humectants, and skin conditioners. PEGylation occurs when PEGs are attached to numerous protein medications, allowing for greater solubility for selected drugs. Examples of PEGylated medications are PEG-interferon alpha (Pegintron) and PEG-filgrastim. In addition, PEG is available as a bowel preparation for colonoscopy procedures and as a laxative .

Indications

Polyethylene glycol is indicated for use as an over-the-counter osmotic laxative to relieve occasional constipation. When used in combination with sodium ascorbate, sodium sulfate, ascorbic acid, sodium chloride and potassium chloride, it is used for cleansing of the colon in preparation for colonoscopy in adults.

Pharmacokinetics

PEGs act as nonionic surfactant to decrease surface tension and condition the stratum corneum, thus enhance the diffusion of other molecules or drugs through the skin .

Metabolism

Polyethylene glycol is a metabolically inert laxative that does not undergo intestinal enzymatic degradation or bacterial metabolism. Proportion of absorbed PEGs may be metabolized to lower oligomers, glycolic acid, hydroxyglycolic acids and the diglycolic acids homologs, carbon dioxide that is exhaled, and to a minor extent, oxalic acid .