A Review on Transdermal Patches

Abstract

Since the start of life on the earth, humans have applied plenty of substances to their skin as cosmetics and therapeutic agents. However, it was the 20 th century once the skin became used as route for future drug delivery.Today about two third of drugs (available in market) are taken orally, but these aren’t as effective as required. To enhance upon the features the transdermal drug Delivery system was emerged. Amongst all techniques that transdermal drug delivery systems (TDDS), also referred to as “patches,” are dosage forms designed to deliver a therapeutically effective quantity of drug across a patient’s Skin. It give controlled continuous delivery of drugs via the skin to the systemic circulation. Advantage of transdermal drug delivery system are limitation of hepatic first pass metabolism, improvement of therapeutic potency and maintenance of steady plasma level of the drug. transdermal patch (Skin Patch) uses a special membrane to control the rate At which the liquid drug contained in the reservoir within the patch will pass through the skin and Into the bloodstream. Drugs administered through skin patches include scopolamine (for motion sickness), nicotine (for quitting smoking), estrogen (for menopause and to stop osteoporosis after menopause), nitroglycerin (for angina), and lidocaine to relieve the pain of shingles (herpes zoster).Transdermal patches were developed in the 1970s and the first was approved by the FDA in 1979 for the treatment of motion Sickness. IN 1981, patches for nitroglycerin were approved, and today there exist variety Of patches for drugs such as clonidine, fentanyl, Lidocaine, nicotine, nitroglycerin, estradiol, Oxybutinin, scopolamine, and testosterone. There are combination patches for Contraception, also as hormone replacement. Depending on the drug, the patches typically last from 1to7days. Non-medicated patch markets include Thermal and cold patches, nutrient patches ,skin care patches. Skin patch uses a special membrane to manage the rate at which the liquid drug contained in reservoir within patch will pass through the skin and into the bloodstream. Some drugs should be combined with substances, such as alcohol, that increase their ability to penetrate the skin so as to be used in skin patch. From last twenty years over thirty five transdermal products are approved generating sale of $3.2 billion in 2002,which is predicted to rise to $4.5 billion in 2008. TDDS are adhesive drug-containing devices of defined surface area that deliver predetermined quantity of drug to the surface of intact skin at a programmed rate to reach the systemic circulation. The greatest challenge for transdermal delivery is that only a limited number of medicine are able to administration by this route.Tansdermal route of administration is reflected as one of the potential route for The local and systemic delivery of drugs. Transdermal patches provides better therapeutic effect with minimum facet effects transdermal patches are designed to release the active ingredient at a zero order rate for a period of several hours to days following application to the skin.