In Vitro Passive and Iontophoretically Assisted Transport of Salbutamol Sulphate Across Synthetic Membranes

Abstract

The passive and electrically assisted transport of salbutamol sulphate through four synthetic membranes was investigated. Two of these were hydrophilic (Visking 18/32 and Celgard-3401®) and two hydrophobic (Celgard-2400® and Celgard-4500®). Significant differences in passive membrane transport were observed. The hydrophilic Celgard membrane gave similar passive transport rates to Visking 18/32. However, slower rates were observed with the hydrophobic membranes, the rate for Celgard-4500 being 4-5 fold smaller than Visking 18/32 and that for Celgard-2400 being negligible over a period of 6 hours. The passive release of salbutamol sulphate from the hydrogel across the hydrophilic membranes was matrix-controlled, whereas the membrane was the rate-limiting element for passive release through the hydrophobic membranes. Application of an electrical potential giving rise to iontophoretic currents in the range 0.100 to 0.500 mA led to an increase in drug transport rate and this effect became larger as the current was increased. The quantity of drug transported in a given time period increased linearly with time for both kind of membranes. However the relative increase in transport induced by current was greatest with the hydrophobic membranes.