PEG400 (Polyethylene glycol 400) is a polymer formed from repeating units of ethylene glycol that is water soluble, low immunogenicity, and biocompatible. PEG400 is a neutral polymer with a molecular weight of 400.

METHODS: Human colorectal adenocarcinoma cells Caco-2 were treated with PEG400 (30 w/v% in 100 μL) for 30 min, and cell growth inhibition was detected by MTT.
RESULTS: PEG400 treatment reduced cell viability, which was 42%±2% compared with the control. [1]

METHODS: To study in vivo activity, Simvastatin (60 mg/kg, aqueous 2% DMSO+30% PEG 400+5% Tween 80) was administered by gavage to C57BL/6J mice once daily for six weeks on a CF diet.
RESULTS: Simvastatin treatment reduced serum cholesterol levels by 18%, and retinal cholesterol and lipoprotein cholesterol levels by 24% and 21%, respectively. [2]
METHODS: To study the effect of Rapamycin on life expectancy, Rapamycin (8 mg/kg in DMSO+5% PEG-400+5% Tween-80) was administered intraperitoneally to 20-21 month old C57BL/6J mice once daily for three months.
RESULTS: Three months of Rapamycin treatment was sufficient to increase the life expectancy of middle-aged mice by 60% and improve their healthy lifespan. [3]