The effect of niosomes and polysorbate 80 on the metabolism and excretion of methotrexate in the mouse.

The effect of non-ionic surfactant vesicle (niosome) encapsulation on the metabolism and urinary and faecal excretion of methotrexate (MTX) in mice has been studied following oral and intravenous administration, and compared with the effects of co-administration of free drug and polysorbate 80, which does not form vesicles. Niosome entrapment reduces the excretion of MTX into urine and bile whereas polysorbate 80 increases its excretion. Monitoring of the levels of MTX and its 7-hydroxy metabolite indicates that entrapped MTX is protected from rapid metabolism in vivo, particularly in niosomes but to a small degree in the micellar systems formed by polysorbate.