Excipient (pharmacologically inactive substance)
What is it?
Polyethylene glycol, referred to as PEG, is used as an inactive ingredient in the pharmaceutical industry as a solvent, plasticizer, surfactant, ointments, and suppository base, and tablet and capsule lubricant. PEG has low toxicity with systemic absorption less than 0.5%.
PEGylation occurs when PEGs are attached to various protein medications, allowing for greater solubility for certain drugs. Examples of PEGylated medications include PEG-interferon alpha (Pegintron) and PEG-filgrastim (Neulasta). PEG is also available as a bowel prep for colonoscopy procedures and as a laxative.
PEG 400 indicates the average molecular weight of the specific PEG at 400. PEG 3350 is a laxative available over-the-counter by the name of Miralax. In this case, PEG is considered an "active" ingredient, even though systemic absorption is less than 0.5%.