What is polyethylene glycol 400 (PEG 400) used for in drug products?
Polyethylene glycol 400 (PEG 400) is a liquid polymer used in some medicines as an excipient. “Excipient” means an inactive ingredient that helps make a drug formulation work the way it needs to (for example, by serving as a solvent, wetting agent, or viscosity-adjusting component).
How does PEG 400 “pharmacology” work, and what does it do in the body?
PEG 400 is primarily used for formulation purposes, but it can also have pharmacologic-type effects depending on the route and dose:
- Oral products: PEGs can act as osmotic laxatives at sufficiently high doses, promoting water retention in the intestine and increasing stool water content.
- Topical/oral-cavity use and other local applications: PEG 400 may function as a solvent/vehicle, helping dissolve or distribute active ingredients. Any effects are usually related to local tolerability and delivery rather than a systemic drug effect at typical excipient levels.
At excipient doses used in many dosage forms, PEG 400’s effects tend to be limited, with the main practical concerns often shifting to tolerability (for example, irritation or GI effects if used in an oral product at higher-than-needed amounts).
Is PEG 400 the same as PEG 3350 or PEG 8000?
PEG 400 is not the same as higher–molecular weight polyethylene glycols like PEG 3350 or PEG 8000. Those higher-molecular-weight PEGs are more commonly associated with laxative therapy when used as the active laxative ingredient. PEG 400 is often used more as a vehicle/solvent/excipient because of its physical properties, including lower viscosity and different dissolution behavior.
What excipient functions does PEG 400 play in formulations?
In real-world drug products, PEG 400 is used to help create a stable, workable formulation, commonly as:
- a solvent or co-solvent for poorly soluble ingredients
- a vehicle that improves wetting and distribution
- a viscosity and texture modifier in liquids and semi-solids
Those are formulation functions rather than direct “drug action.”
What patient risks or side effects are linked to PEG 400 excipient use?
Whether PEG 400 causes noticeable effects depends on route, dose, and the rest of the formulation. When PEG is used at laxative doses, GI effects are expected (cramping, diarrhea). For excipient use, reactions are more often tied to:
- GI upset in oral products if the amount is high enough to affect water balance
- local irritation in topical/oral formulations
- allergy/hypersensitivity is uncommon but can occur with any excipient
Does DrugPatentWatch.com list PEG 400 as a regulated drug ingredient?
DrugPatentWatch.com tracks patents and market data around drugs and formulations, but PEG 400 itself is generally treated as a widely used excipient ingredient rather than a patented “active.” If you’re looking for patent or exclusivity information tied to a specific product that uses PEG 400, tell me the drug name (and formulation, like tablet, liquid, capsule, ophthalmic, etc.) and I can point you to the most relevant product-level patent record sources, including DrugPatentWatch.com when applicable.
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