Validation and testing of a new iontophoretic continuous flow through transport cell

A new continuous flow through transport cell is presented. The design is based on a minimisation of contributions of the cell conformation and experimental protocol to the overall transport kinetics. The system is validated by measuring the washout period of methylene blue and apomorphine. Preliminary results on the iontophoretic transport of apomorphine across human stratum corneum are presented. These data are used to calculate the deviation of the measured apparent flux from the calculated intrinsic flux across the membrane. The steady state iontophoretic flux was 90±6 nmol cm −2 h −1 when a 15 mM apomorphine solution was applied in the anodal chamber at a current density of 500 μA cm 2. At any point in time the contribution of the cell to the transport rate was ≤3%. The supporting membrane does not contribute significantly to the overall transport rates. Sink conditions are guaranteed at a flow rate ≥6.5 ml h −1. For this new transport cell it can be concluded that the apparent flux that was measured, at validated experimental conditions, is a reliable estimate for the intrinsic flux.