In vitro iontophoretic studies using a synthetic membrane

In vitro iontophoretic administration of drugs through a microporous polyolefin membrane with hydrophilic urethane polymerfilled pores was done for the ionized drugs dexamethasone sodium phosphate, hydrocortisone sodium phosphate, and prednisolone sodium succinate, and for a nonionizable drug cortisone acetate. Currents between 0.2 and 0.8 mA were demonstrated to be effective in increasing the transmembrane transport rate compared with passive diffusion for all the ionizable drugs studied. However, these currents failed to show any significant effect on the transmembrane transport rate of the nonionizable drug, cortisone acetate. There was a good linear relationship between the applied current (I, mA) and the transmembrane transport rate (J, micrograms/mL) in the receptor cell for all the ionized drugs (J = 1.97I + 0.70 for dexamethasone sodium phosphate; J = 2.05I + 1.49 for hydrocortisone sodium succinate; J = 2.25I + 1.93 for prednisolone sodium succinate). This in vitro iontophoretic study demonstrated that electric fields interact more efficiently with charged than with uncharged molecules.