TRANSDERMAL DRUG DELIVERY: A WAY FOR BETTER TOMORROW

Transdermal drug delivery is defined as self contained, discrete dosage form which, when applied to the intact skin, deliver the drug, through the skin at controlled rate to the systemic circulation. Despite their relatively higher costs, transdermal delivery systems have proved to be advantageous for delivery of selected drugs such as estrogens, testosterone, clonidine, nitroglycerin, scopolamine, fentanyl, and nicotine. The transdermal route has numerous advantages over the more traditional drug delivery routes. These include high bioavailability, absence of first pass hepatic metabolism, steady drug plasma concentrations, and the fact that therapy is noninvasive. Both topical and transdermal drug products are intended for external use. However, topical dermatologic products are intended for localized action on one or more layers of the skin [e.g.Sunscreens, keratolytic agents, local anesthetics, antiseptics and anti-inflammatory agents]. Although some medication from these topical products may unintentionally reach systemic circulation, it is usually in sub-therapeutic concentrations, and does not produce effects of any major concern except possibly in special situations, such as the pregnant or nursing patient. On the other hand, transdermal drug delivery systems use the percutaneous route for systemic drug delivery. To provide continuous drug infusion through an intact skin, several transdermal therapeutic systems have been developed for topical application onto the intact skin surface to control the delivery of drug and its subsequent permeation through the skin tissue. Keywords: Transdermal, Patches, Dosage forms, Nitroglycerin, Nicotine