Thermodynamics of membrane transport and implications for dermal delivery

Transdermal drug delivery is gaining wider interest as a potential route for the delivery of pharmaceutical products. It offers several benefits over other routes of administration particularly the avoidance of first pass metabolism. However, by its very design skin is an extremely effective barrier to the ingress of foreign materials thus making it difficult to deliver therapeutic doses. There is considerable interest therefore in developing novel methods to improve bioavailability of drugs administered transdermally. Many of the proposed methods involve some invasive modification of the system or have some inherent stability problems. Here we discuss novel methods for the calculation of the thermodynamic parameters which govern transdermal drug delivery and investigate means by which these characteristics can be exploited in order to improve bioavailability of transdermal drugs.