CORRELATION OF THERMODYNAMIC ACTIVITY AND VAPOR DIFFUSION THROUGH HUMAN-SKIN FOR THE MODEL-COMPOUND, BENZYL ALCOHOL

This work tested the potential for predicting percutaneous absorption rates of a volatile penetrant from any vehcile by using thermodynamic activity measurement. Benzyl alcohol was chosen as a non-ideal, H2 bonding, volatile model penetrant. A manual headspace gas chromatherapy method measured benzyl alcohol vapor concentrations and thermodynamic activities above binary mixtures with vehicles: butanol, butyl acetate, isopropyl myristate, isophorone, toluene and propylene carbonate. Benzyl alcohol vapor diffusion through human, abdominal skin was also measured in-vitro for these mixtures. The benzyl alcohol vapor flux was linearly related to the activity, suggesting that percutaneous absorption is controlled by thermodynamic activity when the vehicle has no effect on the stratum corneum barrier.