Transdermal drug delivery: approaches and significance

Abstract

Transdermal drug delivery systems deliver drugs through the skin as an alternative to oral, intravascular, subcutaneous, and transmucosal routes. Potential advantages of transder-mal delivery include, but are not limited to, elimination of first-pass metabolism, steady delivery/blood levels, better patient compliance, reduced systemic drug interactions, possible dose intervention, avoidance of medically assisted drug administration, prolonged drug administration, and overall better therapeutic efficacy. Patches were the primitive form of transdermal drug delivery systems with conceptually simple engineering. The first representative of the transdermal drug delivery system patch design was Transderm-Scop ® to treat motion sickness. The success of the scopolamine transdermal system was followed by approval of the nitroglycerin, fentanyl, estradiol, nicotine, and testosterone transdermal systems. Inception of trans-dermal patch systems paved the way for new medical therapies using existing drugs with the potential for fewer side effects. For example, estradiol patches, with a million users annually, do not cause liver damage, in contrast with oral formulations. 1 As a new medical therapy, transdermal nicotine systems have helped millions of smokers quit smoking and likely increased their lifespan. 2 Over the last three decades, more than 35 patch products have been approved by the US Food and Drug Administration in a wide range of therapeutic areas.