Polysorbate 80: a pharmacological study.

Polyoxyethylene (20) sorbitan monooleate (polysorbate 80, Tween 80), a surfactant, has been widely used as a solvent for pharmacological experiments. In the present study, polysorbate 80 was found to have toxicity of a low order in both the mice and rats when given by i.p. and p.o. routes. It produced mild to moderate depression of the central nervous system with a marked reduction in locomotor activity and rectal temperature, exhibited ataxia and paralytic activity and potentiated the pentobarbital sleeping time. On intravenous administration in dogs, it had a dose-dependent hypotensive effect. Polysorbate 80 did not have a direct stimulant or relaxant effect on either guinea pig ileum or rat uterus, however, it antagonised the contractions induced by acetylcholine, histamine, barium, 5-hydroxytryptamine and carbachol in a dose-dependent manner. A direct relaxant effect was observed on rabbit jejunum. A dose-dependent myocardial depressant effect was observed on guinea pig and rabbit paired atrial preparations. On the electrically-driven guinea pig left atrial preparation, polysorbate 80 exhibited a dose-dependent negative inotropic action. Polysorbate 80 did not induce diuresis in rats upto a dose of 2.5 ml/kg. The results of the present study indicate that polysorbate 80 can neither be used as a solvent for isolated tissue experiments nor when considered for intravenous administration. However, polysorbate 80 can be employed safely as a vehicle for neuropsychopharmacological experiments in doses not exceeding 1 ml/kg.