The distribution and elimination of methotrexate in mouse blood and brain after concurrent administration of polysorbate 80.

This paper describes further exploration of the effect of polysorbate 80 on the absorption, distribution, and elimination of methotrexate (MTX). This study has confirmed the earlier finding that polysorbate 80 could increase the absorption of MTX from the mouse gastrointestinal tract and enhance the drugs uptake into the brain. The experiments reported here suggest that polysorbate 80 has a direct effect on the blood-brain barrier leading to the increased uptake of MTX, which is evident following IV administration. Measurements of MTX excreted in the urine and faeces confirmed the role of polysorbate 80 in facilitating the excretion of MTX into the bile and urine. Polysorbate 80 administered PO did not cause any reduction of plasma volume, thus excluding the possibility that the higher MTX concentrations measured in mice after concurrent administration of polysorbate PO might result from a reduction in blood volume due to osmotic effects. At the doses given, polysorbate 80 appeared not to have a damaging effect on the gastrointestinal mucosa.