Enhanced permeability of keratinized oral-mucosa to salicylic acid with 1-dodecylazacycloheptan-2-one (Azone). In vitro studies in hamster cheek pouch

Enhancing effect of 1-dodecylazacycloheptan-2-one (Azone) on the permeability of keratinized oral-mucosa was investigated in vitro using hamster cheek pouch and salicylic acid as a model mucosa and a model compound, respectively. The in vitro permeability of hamster cheek pouch to salicylic acid was approximately 4.4-times higher than that of the abdominal skin, and the stratum corneum of the cheek pouch isolated by the trypsin-treatment showed the similar permeability to the full-thickness preparation of the cheek pouch. Azone-pretreatment enhanced the permeability of both the full-thickness preparation and the stratum corneum of the cheek pouch, and the magnitude of the enhancement was identical. The fluorescence polarization study using 1,6-diphenyl-1,3,5-hexatriene as a probe showed that Azone-treatment increased the fluidity of lipids extracted from the stratum corneum of the cheek pouch. The direct action of Azone during the pretreatment on the stratum corneum, a major barrier for drug permeation, was clarified.