The penetration of hydrocortisone, hydrocortisone 17‐butyrate 21‐propionate, betamethasone, betamethasone 17‐valerate, and clobetasol 17‐propionate through separated human epidermis was compared. The amount of each topical corticosteroid which was released on the skin and penetrated to saline was greater in ethanol solution than propylene glycol solution. The addition of water to the ethanol increased the release of some corticosteroids. The lipid solubility of each corticosteroid correlated well with skin penetration; however, the polarity of each corticosteroid was inversely proportional to skin penetration. The results of the blanching phenomenon caused by the application of these corticosteroids and of their skin penetration suggested to us that the local pharmacological activity of each topical corticosteroid, rather than their skin penetration, related well to their clinical effectiveness.

The conjugation of some phenolic compounds with ten dansyl amino acids was examined and the results indicated the importance of conjugation with the lysine residue. The conjugation of phenolic compounds with monodansyl cadaverine and cadaverine was also studied. The results obtained by these in vitro tests correlated well with those of animal sensitization tests and patch tests on patients with contact dermatitis.

Carbon‐14 labeled nicotinic acid (NA), methyl nicotinate (MN), and butyl nicotinate (BN) were dissolved in distilled water or olive oil vehicles and applied to in vivo and excised guinea pig skin. Four skin conditions were represented by allergic, irritated, tape‐stripped, and normal skin. The amount of chemicals released to, retained by, and penetrating the skin was measured one‐half to twenty‐four hours after application. The penetration of NA was less than that of BN or MN. The release of chemicals to the skin was inversely related to their solubility in vehicles. More chemical was released to in vivo than excised skin. A barrier effect occurring in the lowest part of the horny layer affected NA most, followed by BN, and MN. Release of NA and MN from vehicles was greatest in tape‐stripped skin, followed by irritated, allergic, and normal skin. BN release was not affected by skin conditions.

The influence of 5 liquid, 6 cosmetic and 2 ointment vehicles on the penetration of benzyl alcohol, isoeugenol and methyl isoeugenol through human epidermis was studied. Benzyl alcohol penetrated most rapidly from almost all vehicles. Among liquid vehicles, liquid paraffin provided the best penetration for the 3 compounds. As the ratio of water to ethanol increased in ethanol/water solutions, the penetration of each compound increased. Among cosmetic and ointment vehicles, lotion and milky lotion afforded maximum penetration of each compound with the exception of milky lotion in the case of benzyl alcohol. Macrogol ointment provided the poorest penetration results for the 3 compounds tested.