- Polyethylene glycol (PEG) is a versatile, synthetic, and biocompatible polyether compound widely used across biological, pharmaceutical, chemical, and industrial fields.
- It is composed of repeating units of ethylene oxide (–CH₂CH₂O–) and comes in various molecular weights, ranging from a few hundred to several million Daltons. This variability in chain length gives PEG a wide range of physical properties, from clear viscous liquids (low molecular weight) to waxy solids (high molecular weight), making it highly adaptable for different applications.
- PEG is notable for its non-toxic, non-immunogenic, and water-soluble properties, which make it particularly suitable for biomedical and pharmaceutical use. In medicine, PEG serves several important functions. It is used as a vehicle or solvent for drugs, especially in oral, topical, and injectable formulations. Its ability to improve the solubility and stability of poorly water-soluble drugs has enhanced the efficacy of numerous therapeutics. Additionally, PEG is a key component in osmotic laxatives, where it retains water in the intestinal tract to facilitate bowel movements, as seen in products like PEG 3350 (Miralax).
- One of the most significant innovations involving PEG is PEGylation—the covalent attachment of PEG chains to therapeutic molecules such as proteins, peptides, or drugs. This modification can greatly improve a drug’s pharmacokinetics by increasing its half-life, reducing renal clearance, and minimizing immune recognition. PEGylated drugs, including interferons, enzymes, and monoclonal antibodies, are now a mainstay in treatments for diseases ranging from cancer to hepatitis and genetic disorders. However, concerns have recently arisen regarding anti-PEG antibodies that may reduce the efficacy of PEGylated therapies in some individuals.
- In cell biology and biotechnology, polyethylene glycol is widely used as a fusogen, particularly for inducing cell-cell fusion in the creation of hybridoma cells for monoclonal antibody production or heterokaryons in nuclear reprogramming experiments. PEG induces fusion by dehydrating cell membranes and promoting lipid bilayer mixing, leading to the formation of single cells containing nuclei from different parent cells.
- In cosmetic and personal care products, PEGs serve as humectants, emulsifiers, and solvents, commonly found in skin creams, shampoos, toothpaste, and lubricants. They help maintain moisture, stabilize formulations, and deliver active ingredients. In industrial settings, PEGs are used as lubricants, anti-foaming agents, and plasticizers, and even as heat transfer fluids due to their thermal stability and low volatility.
- Despite its generally recognized safety, PEG has prompted some scrutiny in consumer and clinical settings. Contaminants such as ethylene oxide or 1,4-dioxane, which may remain from manufacturing, can pose health risks if not properly removed. Regulatory agencies monitor and limit such contaminants, especially in pharmaceutical-grade PEG. Additionally, although rare, some individuals can develop hypersensitivity reactions to PEG, especially at higher doses or in repeated exposures.
