ABSTRACT

INTRODUCTION The transdermal route of drug administration offers several advantages, such as reduced first-pass drug metabolism, no gastrointestinal degradation, long-term delivery (>24 hours), and control over delivery and termination. However, only few drug molecules have been formulated into transdermal patches because of the low permeability of the skin (1). The outermost layer, the stratum corneum (SC), forms a barrier against permeation of drugs into the body. This barrier must be altered to maximize the possibilities of transdermal drug delivery. This problem has engaged pharmaceutical scientists, dermatologists, and engineers alike in research over the last few decades (2). High research activity in this field has led to the introduction of a variety of techniques, including formulation-based approaches (3), iontophoresis (4), electroporation (5,6), acoustic methods (7), microneedles (8), jet injection (9), and thermal poration (10) (see Chapter 1). Each of these techniques has its benefits and specific applications.