chapter  62
Skin Impedance–Guided High Throughput Screening of Penetration Enhancers: Methods and Applications
ByAmit Jain, Pankaj Karande, Samir Mitragotri
Pages 14

The idea of delivering drugs through the skin is as old as human civilization, but the excitement has increased in recent times after the introduction of the first transdermal patch in 1970s. Although transdermal route of drug administration offers several advantages such as reduced first-pass drug metabolism, no gastro-intestinal degradation, long-term delivery (>24 hours) and control over delivery and termination, only few drug molecules have been formulated into transdermal patches (1). The cause of this imbalance between the benefits of this route and the number of products in the market lies in the skin itself. Skin’s topmost layer, Stratum Corneum (SC), forms a barrier against permeation of xenobiotics into the body and water evaporation out of the body. This barrier must be altered to maximize the advantages of transdermal route of drug administration. This has engaged pharmaceutical scientists, dermatologists, and engineers alike in research over the last couple of 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), acoustical methods (7), microneedles (8), jet injection (9), and thermal poration (10).