ABSTRACT
The advantages of transdermal drug delivery over conventional routes of drug delivery are many folds. The transdermal route provides an alternative route to oral administration. Drugs delivered by this route avoid digestion in the gastrointestinal tract (GI), local metabolism related to the GI route, and hepatic first pass metabolism. There are many varieties of chemical penetration enhancers for transdermal transport. Transdermal iontophoresis is the enhanced transport of drug across skin by an externally applied electric field. Transdermal electroporation is a method to induce transient small pores in the skin to enhance transdermal drug delivery with the application of high electric field pulses. Sonophoresis enhances transdermal transport through the mechanisms of pore induction, convection, and stratum corneum lipid alteration. Technology in medicine is defined as the application and evolution of basic science to clinical practice. Two main types of transdermal patches are commonly used: drug reservoir patch and drug-in-adhesive patch.
