Membranes in Drug Delivery

This chapter is aimed to illustrate and to discuss membrane applications in the delivery field focussing the attention on the mechanisms ruling mass transport. Accordingly, membranes physical characteristics such as intrinsic topological structure, viscoelastic nature and membrane-drug interaction are considered. In this frame the continuity equation is presented and particularised in relation to different scenarios such as polymeric matrices, osmotic systems and electrotransport. On the basis of this theoretical frame, some examples of mathematical models serving to get drug diffusion coefficient by means of data fitting are shown. In particular, it is stressed the necessity of experimentally match the assumptions on which interpretative models relay. Among the great variety of membrane applications in the delivery field, those related to the oral and transdermal administration route are presented and discussed. Consequently, coating processes, asymmetric membranes and membranes devoted to colon delivery are presented for what concerns oral delivery systems. Membranes for passive diffusion delivery systems and physically enhanced delivery systems constitute the topic of transdermal administration route. The final part of this chapter is devoted to some membranes applications in the nano-medicine field. In particular, the restenosis prevention and the bioavailability enhancement due to nano-crystals will be dealt with