Vol 9, Issue 6, 2016 Online - 2455-3891 Print - 0974-2441 MANAGEMENT OF PAIN USING TRANSDERMAL PATCHES - A REVIEW LEYA MATHEWS 1 , ANITHA ROY 2 * 1 Department of Dental Surgery, Saveetha Dental College and Hospitals, Chennai, Tamil Nadu, India. 2 Department of Pharmacology, Saveetha Dental College and Hospitals, Chennai, Tamil Nadu, India. Email: anitharoypeeter@yahoo.co.in Received: 29 June 2016, Revised and Accepted: 28 July 2016 ABSTRACT Transdermal delivery is a non-invasive route of drug administration through the skin surface that can deliver the drug at a predetermined rate across the dermis to achieve a local or systemic effect. It is potentially used as an alternative to oral route of drugs and hypodermic injections. Analgesics are mostly used for various diseases as most of them are associated with severe or mild pain. The use of analgesics as a pain relief patch is now being used commonly. A transdermal analgesic or pain relief patch is a medicated adhesive patch used to relieve minor to severe pain. Currently, the patches are available for many opioids, non-opioids analgesics. local anesthetics, and antianginal drugs. The drugs include fentanyl, buprenorphine ketoprofen, diclofenacepolamine, piroxicam, capsaicin, nitroglycerine, and lignocaine. They are available as both matrix and reservoir patches. This review explores the various drugs used to manage pain and their route of administration in terms of frequency, complications, and effects. Keywords: Pain, Transdermal drugs, Transdermal patches, Safety. INTRODUCTION Transdermal drug delivery system, now often known as patches, is a non-invasive way of delivering medications across the dermis or skin surface. It is potentially used as an alternative to administer oral route of drugs and hypodermic injections. This drug delivery system can deliver an analgesic at a predetermined rate across the skin to receive a systemic or a local effect. Transdermal patches are not a new concept. It was first used for systemic delivery, a three day patch, scopolamine to treat motion sickness, approved in the United States in 1979. A decade later, the success of nicotine patches brought in more awareness and usage of transdermal drugs [1]. Today, over 35 drugs are used as transdermal patches, with at least 13 approved molecules. The therapeutic horizon of transdermal patches is now expanding to include hormone replacement, analgesic, relief of chest pain by heart disorders, smoking cessation, and neurologic disorders. Transdermal patches have a number advantages over oral and hypodermic injections. It provides better biocompatibility in the first pass hepatic metabolism. Increased flexibility in drug administration by patch removal, painless application, and prolonged application for 1 week are other advantages. However, this drug delivery system has not completely achieved its potential due to few limitations. Local irritation and sensitization of the skin may limit the number of drugs. Successful transdermal drugs have molecular masses that are only up to a few hundred Daltons, thereby limiting the dosage of the drug too. Difficulties in delivering hydrophilic drugs, expense of medication, and delayed absorption are other disadvantages [2]. Transdermal drugs will continue to gain popularity along with further improvements to improve safety and efficacy. A further major step forward will be the production of patches delivering peptide and even protein substances including insulin, growth hormone, and vaccines [4]. Transdermal patches can be categorized into three categories - first generation, second generation, and third generation. First generation transdermal patches They are the first set of patches and have been used much in clinics. The transdermal patch design consists of the drug in a reservoir that is enclosed on one side with impermeable backing and adhesive, which contacts the skin [4]. However, due to certain limitations, not all drugs with suitable properties can be delivered. The first generation transdermal patches are limited primarily to the skin barrier that is stratum corneum. Hence, the drugs should be of low molecular weight, lipophilic, and efficient at low doses. Second generation transdermal patches Advances in patches to increase the skin permeability, reduce damage to the deeper tissues, and provide better transport into the skin. Certain modifications such as chemical enhancers, non-cavitation ultrasound, and iontophoresis have disturbed the balance in the approach to increase the delivery and also protect the deeper tissues at the deeper level. Chemical enhancers - they disrupt the highly ordered bilayer of the stratum corneum by inserting amphiphilic molecules to help in better permeation. This, however, can produce skin irritation. Iontophoresis - they involve administration of drugs into the stratum corneum under low voltage current. They do not disturb the skin barrier, so they can be used for small molecules that carry a charge and some macromolecules up to a few Daltons. Rate of drug delivery can be controlled using a microprocessor. Non-cavitation ultrasound - physical therapists discovered that massaging anti-inflammatory agents into the skin using ultrasound can increase the efficacy as a skin permeation enhancer [5]. The effects of ultrasound have been limited to small lipophilic molecules. It has been limited due to its associated tissue heating, which can damage the deeper tissue. Third generation transdermal patches It involves further advances to improve the skin penetration of drugs and also protection of deeper tissues. Microneedles, thermal ablation, and micro derma abrasion have been experimented in human clinical trials to deliver the macromolecules, therapeutic proteins, and vaccines. Review Article © 2016 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2016.v9i6.13775