Transdermal Delivery a Preclinical and Clinical Perspective of Drugs Delivered via Patches

As skin is a readily accessible organ of the body, it acts as the portal of entry for extraneous substances for their effective transdermal delivery. Possessing various advantages, it has the limitation of low permeability of drugs across it, limiting the efficacy of drugs. Therefore, various carrier systems have been developed to enhance the permeation deep into the systemic circulation. The potential of using the intact skin as the portal for drug administration to the human body has been recognized for several decades. With the advent of modern era of pharmaceutical dosage forms, transdermal drug delivery system (TDDS) established itself as an integral part of novel drug delivery systems. Transdermal patches are polymeric formulations which when applied to skin deliver the drug at a predetermined rate across dermis to achieve systemic effects. The number of drugs formulated in the patches has gained tremendous potential to deliver the drug via transdermal route. Controlled absorption, more uniform plasma levels, improved bioavailability, reduced side effects, painless and simple application and flexibility of terminating drug administration by simply removing the patch from the skin are some of the potential advantages of transdermal system. Numerous studies have been conducted to evaluate the potential of patches for efficacious transdermal delivery. The present review focuses on the preclinical and clinical aspects of drug delivery of various therapeutic categories through transdermal patches emphasizing enhanced safety and efficacy via these carriers. Keyword: Flux, Matrix, Permeation, Patches, Skin, Transdermal.