Polyindole:poly(4-styrenesulfonic acid) loaded agarose hydrogel for methotrexate sodium transdermal delivery via iontophoresis

The iontophoretic transdermal drug delivery system is an alternative route to the usual injection route. Agarose, a biopolymer with self-gelation, was served as a drug reservoir due to its well-connected porous structure and non-toxicity. PIn:PSS, a water soluble conductive polymer, was used as a drug carrier. Methotrexate sodium (MTX) loaded PIn:PSS (MTX-PIn:PSS) was embedded in the AG gel to investigate the in-vitro drug release and in vitro drug release-permeation under the effects of the matrix pore sizes, electric fields, and pHs. The amount of MTX released increased with decreasing AG concentration due to a larger pore size. In the presence of electric field, the higher amount and rate of MTX release were obtained due to the electro repulsive force and the electroosmotic effect. Incorporating PIn:PSS as the drug carrier was shown here to improve the MTX release. The amount and rate of MTX release-permeation became lower due to the porcine skin and the low pH, but were improved under the applied electric field. The MTX-PIn:PSS in the AG gel is shown here to be an effective drug carrier to enhance and control the MTX release-permeation in the iontophoretic transdermal delivery.