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Tramadol (marketed as Ultram, and as generics) is an opioid pain medication used to treat moderate to moderately severe pain.〔(【引用サイトリンク】url=http://www.drugs.com/monograph/tramadol-hydrochloride.html )〕 When taken as an immediate-release oral formulation, the onset of pain relief usually occurs within about an hour. It has two different mechanisms. First, it binds to the μ-opioid receptor. Second, it inhibits the reuptake of serotonin and norepinephrine.〔(Now What? DEA Tosses Tramadol in Schedule IV ), By Nadia Awad, MedPage Today, Jul 10, 2014〕〔 Serious side effects may include seizures, increased risk of serotonin syndrome, decreased alertness, and drug addiction.〔 The risk of serotonin syndrome appears to be low. Common side effects include: constipation, itchiness and nausea, among others. A change in dosage may be recommended in those with kidney or liver problems. Its use is not recommended in women who are breastfeeding or those who are at risk of suicide.〔 Tramadol is marketed as a racemic mixture of both ''R''- and ''S''-stereoisomers.〔 This is because the two isomers complement each other's analgesic activity.〔 It is often combined with paracetamol (acetaminophen) as this is known to improve the efficacy of tramadol in relieving pain.〔 Tramadol is metabolised to ''O''-desmethyltramadol, which is a more potent opioid. It is of the benzenoid class. Tramadol was launched and marketed as Tramal by the German pharmaceutical company Grünenthal GmbH in 1977 in West Germany, and 20 years later it was launched in countries such as the UK, U.S., and Australia. ==Medical uses== Tramadol is used primarily to treat mild-severe pain, both acute and chronic.〔 Tramadol is recommended for the management of pain in fibromyalgia by the European League Against Rheumatism. Its analgesic effects take about one hour to come into effect and 2–4 hours to peak after oral administration with an immediate-release formulation.〔 On a dose-by-dose basis tramadol has about one-tenth the potency of morphine and is approximately equally potent when compared to pethidine and codeine. For pain moderate in severity its effectiveness is equivalent to that of morphine; for severe pain it is less effective than morphine.〔 These painkilling effects peak at about 3 hours, post-oral administration and last for approximately 6 hours.〔 These analgesic effects are only partially reversed by naloxone, hence indicating that its opioid action is unlikely the sole contributing factor; tramadol's analgesic effects are also partially reversed by α2 adrenergic receptor antagonists like yohimbine and the 5-HT3 receptor antagonist, ondansetron.〔 Pharmacologically, tramadol is similar to levorphanol and tapentadol in that it not only binds to the mu opioid receptor, but also inhibits the reuptake of serotonin and norepinephrine〔 due to its action on the noradrenergic and serotonergic systems, such as its "atypical" opioid activity. Available dosage forms include capsules, tablets, including extended release formulations and injections.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「tramadol」の詳細全文を読む スポンサード リンク
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