The Effect of Temperature and Humidity on the Penetration of C14 Acetylsalicylic Acid in Excised Human Skin.

That the percutaneous absorption of substances can be facilitated by increasing the temperature and relative humidity of the skin seems to be generally accepted but rarely confirmed or refuted experimentally. Occlusive dressings are now in widespread use to enhance penetration of substances and probably owe their effectiveness to an increase in both temperature and moisture. Several authors (5—10) have mentioned increased skin permeability brought about by occlusion. Whitehouse, Hancock, and Haldane (1) showed an increase in the rate of percutaneous absorption of oxygen on raising the environmental temperature of man. In normal human male subjects, Brown and Scott (2) could demonstrate an increase in the absorption of methyl salicylate due to temperature increase. Hydration of the skin also produced an increase in absorption. Renshaw (3) demonstrated the role of heat and moisture in augmenting the effect of vesicant vapors on human skin. Cullumbine (4) also concluded that wet skin was more susceptible to the effects of vesicant gases but stated that the effect of temperature was more complex. Onken and Moyer (13) recently showed that the rate of water vapor transpiration through excised human skin at 40° C. is about six times that at 9° C. Cronin and Stoughton (11) stated that soaking the skin increased the penetration six fold for cold soaking and 12 fold for hot soaking in vivo and six fold for both in vitro (14). We will show that increasing either temperature or relative humidity increases percutaneous absorption in vitro. This work involves in vitro technics which have been developed from those of Treherne (12), I. Blank (15), and Cronin (14).