Polysorbate 20 is a polyoxyethylene (POE)-type nonionic surfactant[2].In Vitro: Addition of Polysorbate 20 can modify lignin surface properties to change its hydrophobicity, hydrogen bonding ability and surface charges, thus reducing the non-productive adsorption of proteins.
Polysorbate 20 (0.35%-0.7% w/w) added to 0.05 mol/L of phosphate buffer pH 6.5 dramatically increased the apparent solubility of the drug from 0.8 μg/ml even to 353 μg/ml, while its effect in lower pH or in water was much smaller (20 μg/ml in pH 4.5). The increased concentration of phosphate salts (0.2 mol/l) at pH 6.5 in the presence of 0.7% of polysorbate 20, resulted in further increase of candesartan cilexetil solubility to 620 μg/ml[2].