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CAS 25322-68-3 Low-MW PEG Solvent / Co-Solvent Low-MW PEG Solvent / Co-Solvent

Polyethylene Glycol 400 (for injection)

IUPAC: Poly(ethylene glycol), average Mn 400 View on PubChem
CAS NUMBER
25322-68-3
MOL. FORMULA
H(OCH2CH2)nOH (n˜8.2-9.1)
MOL. WEIGHT
380-420 g/mol
Scientific Overview

PEG 400's hydrophilic ether backbone allows it to dissolve both polar and moderately non-polar drug molecules, making it one of the most widely used parenteral and oral co-solvents. It is FDA-approved for oral, topical, and intravenous use across numerous marketed drug products.

Polyethylene Glycol 400 is a low-molecular-weight, water-miscible liquid PEG grade widely used as a co-solvent in injectable, oral, and topical pharmaceutical formulations, valued for its low toxicity and broad solubilizing power for lipophilic APIs.

Full Technical Data
Chemical Name Polyethylene Glycol 400 (PEG 400; Macrogol 400)
CAS Number 25322-68-3
IUPAC Name Poly(ethylene glycol), average Mn 400
Molecular Formula H(OCH2CH2)nOH (n˜8.2-9.1)
Molecular Weight 380-420 g/mol g/mol
Density 1.128 g/cm³
Flash Point 238°C
Reaction Scheme
Ethylene Oxide
NA
NA
Polyethylene Glycol 400
NA
Commercial Applications

Injectable Co-Solvent

Solubilizes lipophilic APIs in IV and IM formulations, e.g. certain anticonvulsant and chemotherapy injectables.

Oral Liquid & Softgel Vehicle

Used as a solvent/vehicle in oral solutions and soft-gelatin capsule fill formulations.

Topical & Ointment Base

Functions as a humectant and vehicle component in topical creams, ointments, and suppositories.

Tablet Coating & Plasticizer

Used as a plasticizer in film-coating formulations for solid oral dosage forms.

Market Therapeutic Focus
LOW-MW PEG SOLVENT / CO-SOLVENT PHARMACEUTICAL MANUFACTURING INJECTABLE & PARENTERAL FORMULATION ORAL SOLID & LIQUID DOSAGE FORMS SPECIALTY EXCIPIENTS CRO/CDMO
Scientific Literature

Polyethylene Glycols and Their Applications in Drug Delivery

Authors: D'souza, A.A.; Shegokar, R.

Expert Opin. Drug Deliv.

Toxicological Aspects of Polyethylene Glycols

Authors: Fruijtier-Pölloth, C.

Toxicology

PEG 400 as a Co-Solvent in Oral and Parenteral Formulations

Authors: Strickley, R.G.

Pharm. Res.

Peer Queries & FAQs
Why is PEG 400 used instead of higher-MW PEGs in injectables?
Its liquid state at room temperature and low viscosity make it easy to formulate and inject, unlike solid higher-MW PEG grades.
Is PEG 400 safe for repeated IV administration?
Yes, within regulatory dose limits; however, high cumulative doses have been associated with osmotic effects and rare hypersensitivity in some patients.
What distinguishes PEG 400 from PEG 300 and PEG 3350?
All share the same polymer backbone and CAS number; they differ in average molecular weight/chain length, which determines viscosity, physical state, and clearance route.
What is the recommended storage condition?
Store in a tightly sealed container at room temperature, protected from oxidation and moisture.

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