Penetration through excised human epidermis of six phenolic, four benzyl, two salicylate and six cinnamic compounds was examined. A considerable difference in penetration of the compounds tested was observed. Benzyl alcohol penetrated most rapidly. Solubility in water and octanol of each compound was studied. All compounds were freely soluble in octanol. A high correlation between water solubility and percent penetration through human epidermis of compounds was observed. The percent penetration of compounds was not related to allergenic potency.
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.
The storage stability of triflumizole and its metabolite, FM-6-1, in the final solutions of cleaned sweet pepper and lily scale was studied in dark and light conditions. Triflumizole and FM-6-1 rapidly decreased with storage time in the final acetonitrile solution of sweet pepper.After 168 hr, triflumizole and FM-6-1 decreased to 3. 7% and 33. 9%, respectively. The decrease was more remarkable during the storage at 30°C than at 5°C, and in the light than in the dark. In the lily-scale solution, triflumizole and FM-6-1 did not degrade even at 30°C in the laboratory light. The difference of triflumizole and FM-6-1 in stability in the solutions of sweet pepper and lily scale may be attributed to the content of chlorophyll extracted from these crops. Triflumizole and FM-6-1 also decreased with time in an acetonitrile solution containing chlorophyll in the light, and degraded almost 1-to 2-fold faster than in the sweet-pepper solution.In both sweet-pepper solution and chlorophyll solution, new compounds appeared as triflumizole and FM-6-1 decreased and increased with storage time. The results indicated that the stability of triflumizole and FM-6-1 in the final acetonitrile solution of sweet pepper was affected by chlorophyll present in the solution, storage temperature and light.
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