PEG 400 is a strongly hydrophilic polyethylene glycol used as an excellent solvent for a large number of substances that do not readily dissolve in water. PEG 400 is widely used in a variety of pharmaceutical formulations.
Treatment of Fischer 344 rats with PEG400 at a constant volume of 1.0, 2.5 or 5.0 mL/kg body weight/day 5 days/wk for 13 week does not result in any mortality attributed to chemical toxicity or changes in haematology or clinical chemistry findings[1].
References:
[1]. Hermansky SJ, et al. Effects of polyethylene glycol 400 (PEG 400) following 13 weeks of gavage treatment in Fischer-344 rats. Food Chem Toxicol. 1995 Feb;33(2):139-49.