Polyethylene glycol, referred to as PEG, is used as an inactive ingredient in the pharmaceutical industry as a solvent, plasticizer, surfactant, ointment and suppository base, and tablet and capsule lubricant.
PEG "400" indicates that the average molecular weight of the specific PEG is 400.
Viscosity: 90.0 cSt at 25 °C, 7.3 cSt at 99 °C
PEG 400 is soluble in water, acetone, alcohols, benzene, glycerin, glycols, and aromatic hydrocarbons, and is slightly soluble in aliphatic hydrocarbons.
PEG 400 is absorbed by both passive diffusion and by solvent drag, with the latter accounting for a greater fraction of the absorptive drive under normal conditions. Polyethylene glycol 400 uses aqueous pathways for its permeation across the intestinal epithelium.