TRANSDERMAL DRUG DELIVERY ADHESION AS A CRITICAL PARAMETER

Abstract

Transdermal drug delivery system (TDDS), also known as “patches”, are the dosage forms designed to deliver a therapeuticall y effective amount of drug across a patient’s skin. The adhesive of the transdermal drug delivery system is very crucial to the safety, efficacy and qua lity of the product. Recently, it has been recognized that the skin can also serve as the port of admini stration for systemically active drugs. The drugs applied topically are first absorbed into the blood stream and then are transported to the target tissues. Now, it is becoming e vident that the benefits of intra venous infusion can be closely duplicated by using skin as the port of drug administration to provide continuous transdermal drug infusion into the systemic circulation. One of the objectives of TDDS is the maintenance of blood concentration of drug at therapeutic level by means of controlled permea tion throughout the skin during a long period of time and using only one administration. The drug input can be terminated at any point of time by just removing the patch. Rate of drug release from the TDDS is normally much greater than the amount that the skin can possibly absorb. Hence, even if there is a variation in skin permeability, a constant rate of drug input into the circulation is achieved. This artic le provides an overview of type of transdermal systems, role of adhesion, possible adhesion failur es and the measurement of adhesion. In vitro techniques like peel adhesion, tack and shear strength are discussed. Adhesion needs to be a critical parameter for designing a transdermal drug delivery system in order to provide good quality and efficacy to t he patient. This review also covers a brief outline of various components of a patch, their advantages, when the patch should be used and when their use should be avoided.