Challenges Facing Transdermal Drug Delivery Systems:A Conceptual Approach

Transdermal drug delivery systems (TDDS) have become a proven technology throughout the past two decades. TDDS offers significant benefits compared to other, more conventional dosage forms; it is noninvasive, painless and more convenient for the patient; it avoids first-pass metabolism in the liver; it is not affected by food intake or gastric acidity; and there is the possibility of immediate withdrawal of the treatment in case of toxicity. In addition, TDDS enable controlled release of the drug and provide a steady blood level over a long term duration ranging from a few hours to one week. Despite the advantages, of TDDS there are some important obstacles and challenges that TDDS faces. The extent and rate of percutaneous drug absorption and transportation are influenced by various factors including skin physiology, physicochemical properties of drugs and excipients, as well as fabrication and design of the delivery systems. The goal of this article is to review some of these important obstacles and challenges that transdermal drug delivery system faces and to discuss how these relate to transdermal products.