Transdermal analgesic patch
A transdermal analgesic or pain relief patch is a medicated adhesive patch used to relieve minor to severe pain. There are two primary types of analgesic patches: patches containing counterirritants, which are used to treat mild to moderate pain, and patches containing fentanyl, a narcotic used to relieve moderate to severe pain in opioid-tolerant patients.
Counterirritant patches contain ingredients such as capsaicin, methyl salicylate, camphor, or menthol, which are thought to mask pain signals by causing other sensations (itching, warmth, or cooling) in the areas they are applied to. In the United States, patches sold under the brand name Salonpas are approved by the Food and Drug Administration under a New Drug Application (NDA) for the treatment of mild to moderate pain caused by soft tissue injury (e.g. strains and sprains), arthritis, or backache. While Salonpas patches may provide some relief, the effects are not strong and the evidence supporting their efficacy is weak. 
Other products, including brand names such as Bengay and Mentholatum, which are not covered by NDA, indicate relief of minor pain. Counterirritant patches are sold over the counter and do not require a prescription. Other over-the-counter products marketed for the relief of minor injury or arthritis pain include Absorbine Jr. Pain Relief, Excedrin Cooling Pads, and Icy Hot Patches.
In Japan Salonpas, produced by Hisamitsu Pharmaceutical, remains a popular brand. Other manufacturers, including Yutoku Pharmaceutical, SS Pharmaceutical, and Suzuki Nippondo also produce similar over-the-counter patches containing methyl salicylate or glycol salicylate.
In Australia, patches sold under the brand names Eco Pain, and Dencorub are approved by the Therapeutic Goods Administration and listed on the Australian Register for Therapeutic Goods (ARTG) as a Class 1 Medical Device. They are approved for sale over-the-counter for the treatment of mild pain caused by soft tissue injury (e.g. strains and sprains), arthritis, or backache.
Fentanyl transdermal patches are sold under the brand name Duragesic, or as generic equivalents. Fentanyl is an opioid with rapid onset of pain relief; it is often used to treat breakthrough pain. Duragesic and similar patches release fentanyl through the skin. A patch may provide pain relief for up to 72 hours.
Several deaths or life-threatening overdoses have been linked to misuse of fentanyl patches. Fentanyl patches are indicated only for patients with moderate to severe chronic pain who have been taking regular narcotic pain medication for more than a week and who are considered opioid-tolerant. Overdose can occur when patients use more patches than prescribed, change the patches too frequently, or expose the patch to heat.
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