Prediction of cathodal iontophoretic transport of various anions across excised skin from different vehicles using conductivity measurements.

Solute concentration, buffer concentration, applied pH and buffer constituents affect the cathodal iontophoresis of salicylate, benzoate and butyrate across excised skin. Experiments were conducted in which the iontophoretic flux of salicylate was measured across excised human skin with variations in salicylate concentration, donor solution pH, buffer concentrations and buffer consitutents. The conductivity of these solutes and of solutions described in studies on the iontophoresis of benzoate and butyrate were then measured. The observed variations in salicylate, benzoate and butyrate fluxes across a range of conditions were found to be related to the ratio of specific conductance of the solutes in deionized distilled water to that in the buffer solution containing the solutes. The present results suggest that conductivity of solutes in vehicle solutions is one means of predicting the iontophoretic flux of solutes from different vehicle compositions.