| Summary: | This study investigated transdermal drug delivery mechanisms of pectin and pectin-oleic acid (OA) gels and their effects on skin barrier treated by microwave. Hydrophilic pectin-sulphanilamide gels, with or without OA penetration enhancer, were subjected to drug release and skin permeation studies. The skins were untreated or microwave-treated, and characterized by infrared spectroscopy, raman spectroscopy, thermal, electron microscopy and histology techniques. Unlike solid film, skin treatment by microwave at 2450 MHz demoted drug permeation especially from OA-rich pectin gel. The pectin-skin binding was facilitated by gel with freely soluble pectin molecules instead of solid film with entangled chains. It was promoted when microwave fluidized stratum corneum into structureless domains, or OA extracted endogenous lipid fraction and formed separate phases within intercellular lipid lamellae. This led to a remarkable decrease in transdermal drug permeation. Microwave-enhanced transdermal delivery must not be implemented with pectin gel. In skin treated by microwave, the penetration enhancer in gel can act as a permeation retardant.
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