Edward Stone (natural philosopher) piece of bark from a willow tree and was struck by its extremely bitter taste. Knowing that the bark of the Peruvian cinchona tree − from which quinine (used in the treatment of malarial fevers) is derived − has a similarly bitter taste, he surmised that the willow might also have therapeutic properties. Stone's interest in willows was due to the ancient "doctrine of signatures" – whereby the cause of a disease offers a clue to its treatment. According to Stone: "As this tree delights in a moist or wet soil, where agues chiefly abound, the general maxim that many
Transdermal analgesic patch 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