Non-ionic surfactant vesicles (niosomes) prepared from a non-ionic surfactant, cholesterol and dicetyl phosphate and containing methotrexate (MTX) have been administered to mice. Given intravenously the niosomes prolong the levels of MTX in the blood, large amounts of the drug being taken up by the liver. There was also an increased uptake of MTX into the brain, perhaps due to an effect of the niosome components on the permeability of the blood brain barrier. Absorption of the drug from the gastrointestinal tract following oral ingestion, appeared to be increased at some doses; most of the entrapped MTX was taken up by the liver, but uptake of MTX into the brain was also increased. The metabolic profile of the drug is altered by the niosomes which appear to prevent the rapid formation of 7-hydroxy methotrexate.

Synopsis Although aqueous dispersions of lipids in the form of particles having a lamellar structure (liposomes) are already known as excellent vehicles for pharmaceutical substances, their usefulness in cosmetic formulations has not been demonstrated. The present work shows the advantages obtained by application of such systems to the skin, and in particular the use of non-ionic lipids in aqueous dispersions. Thus, in comparison with classical formulations such as emulsions, these systems exhibit lower toxicity and permit closer control of the availability of active substances at the stratum corneum. As examples, compositions suitable for skin moisturising and for tanning products are presented.

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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.