Polyethylene Glycol PEG

Polyethylene Glycol (PEG) is a synthetic polyether compound that has a wide range of applications in pharmaceuticals, cosmetics, industry, and biotechnology. Here's a detailed overview:

Chemical Description

• Chemical Name: Polyethylene glycol

• Chemical Formula: H(OCHCH)OH

• Molecular Structure: A repeating unit of ethylene glycol (CHCHO)

• Molecular Weight (MW): Varies based on the number of repeating units (n). Common grades include PEG-200, PEG-400, PEG-600, PEG-3350, PEG-8000, etc.

  • Low MW PEGs (PEG-200 to PEG-600) are liquids.

  • High MW PEGs (PEG-1000 and above) are waxy solids.

Physical & Chemical Properties

• Appearance: Colorless, odorless, viscous liquids or waxy solids depending on MW.

• Solubility: Highly soluble in water, many organic solvents (alcohols, acetone), but insoluble in hydrocarbons.

• Hygroscopic: Absorbs water from the air.

• Non-volatile and chemically stable.

• Biodegradability: PEGs are generally biodegradable, though the rate depends on MW and environmental conditions.

Uses and Applications

1. Pharmaceuticals

• Laxatives: PEG-3350 is commonly used in over-the-counter and prescription laxatives (e.g., MiraLAX).

• Drug Delivery: Used as a solvent, vehicle, or base in oral, topical, and injectable formulations.

• PEGylation: The process of attaching PEG chains to drug molecules (e.g., proteins, enzymes) to improve:

  • Solubility

  • Stability

  • Half-life

  • Reduced immunogenicity

2. Cosmetics and Personal Care

• Used in creams, lotions, toothpaste, deodorants, etc. as:

  • Moisturizers (humectants)

  • Emollients

  • Solubilizers

  • Surfactants

3. Industrial Uses

• Lubricants and anti-foaming agents

• Plasticizers in rubber and plastics

• Binders in ceramics and other materials

• Ink and paint formulations

4. Biotechnology and Research

• Cell fusion and hybridoma technology

• Protein precipitation in purification processes

• Cryopreservation of cells and tissues

Safety and Toxicity

• PEGs are generally regarded as non-toxic and non-irritating, although effects vary with MW.

• Low MW PEGs can be absorbed through the skin or mucosa, while high MW PEGs are mostly inert.

• In high doses (e.g., laxative use), may cause bloating, gas, diarrhea.

• Hypersensitivity is rare but possible (e.g., anaphylaxis after PEGylated drugs or vaccines).

Environmental Impact

• PEGs are water-soluble and usually biodegradable, but large-scale industrial use can raise concerns about aquatic toxicity depending on formulation and additives.

Regulatory Status

• Approved by regulatory bodies like the FDA, EMA, and other global health agencies for various uses, including oral, topical, and injectable products.