Chapter 5 - Transdermal drug delivery systems: principles, design, and applications

Abstract

A transdermal drug delivery (TDD) system is a route of controlled system of drug delivery which is intended to be the most efficient route through the most accessible drug delivery in the human structure, known as the skin. TDD exploits a potential interest as a drug delivery technique that provides a non-invasive method, a simple, convenient mode of application, reduces any side effect, and increase bioavailability. Patient compliance for this procedure is mostly high, exclusively in young and elderly people, and is optional for groups of patients who are unable to swallow or suffering from nausea or emesis. However, some constrictions prevent the drug delivery through the skin straight to a specific site which is one of the layers of the skin itself known as stratum corneum. This outermost skin layer that interfaces outside environment, acts as main human body barrier that prevents unwanted substances and microorganisms from entering the body, and helps the body from losing plenty of water from exiting the body. Therefore, this chapter will discuss the principles, designs, and applications of TDD systems to overcome the limitation of this route of drug delivery through the several layers of skin. The content of this chapter includes the following subtitles: (1) Introduction, (2) Structure of skin and barriers, (3) Permeation through skin, (4) Factors affecting permeation, (5) Permeation enhancers, (6) Basic components of TDDS, (7) Formulation approaches and evaluation, (8) Advantages and disadvantages, (9) Future prospects.