Controlled drug delivery through tailor-made blend polymeric membranes.

For drugs with short half-lives, transdermal delivery provides a continuous noninvasive mode of administration. For charged drug molecules, the transdermal delivery can be assisted by the application of direct constant current, which drives the drug through the skin by electrostatic repulsion (method called iontophoresis) [1]. An important component of a drug delivery patch is the artificial membrane, which is in contact with the skin and provides controlled drug delivery [2]. In the present work, we study the passive (no current application) and iontophoretic drug transport through tailor-made membranes prepared by blending sulfonated poly(ether ether ketone) (S-PEEK) and poly(ether sulfone) (PES) polymers, at various ratios. The S-PEEK contains negatively charged sulfo-groups, which can be used for the transport of positively charged drugs. When the S-PEEK is blended with the nonconductive PES, its swelling is reduced and the drug delivery can be regulated [3]. Timolol (TM), a nonselective beta-adrenergic blocking agent is used as a model drug molecule. Its pKa is 9.21 and it is therefore positively charged at physiological pH (7.4).