Transdermal delivery of methotrexate: iontophoretic delivery from hydrogels and passive delivery from microemulsions.

In vitro assays were performed to investigate the effectiveness of transdermal administration of methotrexate (MTX) by iontophoretic delivery from two types of hydrogel and passive delivery from two types of microemulsion. Both iontophoretic delivery of MTX from hydrogels and passive delivery from microemulsions were more effective than passive delivery from aqueous solutions of the drug. In the iontophoretic delivery assays, the type of hydrogel used and the concentration of the drug in the loading solution had little influence on effectiveness of delivery. In the passive delivery assays, we used both water/oil (w/o) and oil/water (o/w) microemulsions: effectiveness of delivery was higher from o/w systems. At the end of all assays, significant amounts of MTX were detected in the skin. These results suggest that both hydrogels and microemulsions may be of value for the topical administration of MTX in the treatment of psoriasis.