Experimental verification of the mechanistic model for transdermal transport including iontophoresis

An experimental verification of the previously introduced model for transde rmal transport (Kontturi and Murtomaki, J. Control. Release, 41 (1996) 177) is presented. The model comprises two penetration routes: an aqueous and a lipoidal pathway. Lipophilicity of the drug determines which route the dru g uses. Constant potential iontophoresis can be used to evaluate the relati ve proportions of the two competing pathways. beta-blockers sotalol, timolo l and propranolol, whose water-octanol partition coefficients span three or ders of magnitude, are used as model compounds. Experiments reinforce the p redictions of the model in that iontophoresis enhances the flux of the most hydrophilic drug, sotalol, the most whereas the flux of the least hydrophi lic drug, propranolol, is enhanced the least. The effect of electroosmosis has now been included in the model. (C) 1998 Elsevier Science B.V. All righ ts reserved.