are about 16% higher and the area-under-the-curve levels 36% higher than following a single oral 100-mg dose. Positron emission tomography imaging studies have reportedly found that tramadol levels are at least four-fold higher in the brain than in plasma. Conversely, brain levels of desmetramadol "only slowly approach those in plasma". The plasma protein binding of tramadol is only 4 to 20%; hence, almost all tramadol in circulation is free, thus bioactive. Correspondence to effects
Co-administration of quinidine, a potent CYP2D6 enzyme inhibitor, with tramadol, a combination which results in markedly reduced levels of desmetramadol, was found not to significantly affect the analgesic effects of tramadol in human volunteers. However, other studies have found that the analgesic effects of tramadol are significantly decreased or even absent in CYP2D6 poor metabolizers. The analgesic effects of tramadol are only partially reversed by naloxone in human volunteers, hence indicating that its opioid action is unlikely the sole factor; tramadols analgesic effects are also partially reversed by α2-adrenergic receptor antagonists such as yohimbine, the 5-HT3 receptor antagonist ondansetron, and the 5-HT7 receptor antagonists SB-269970 and SB-258719. Pharmacologically, tramadol is similar to tapentadol and methadone in that it not only binds to the MOR, 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.Tramadol has inhibitory actions on the 5-HT2C receptor. Antagonism of 5-HT2C could be partially responsible for tramadols reducing effect on depressive and obsessive–compulsive symptoms in patients with pain and co-morbid neurological illnesses.
Tramadol, sold under the brand name Ultram among others, is an opioid pain medication used to treat moderate to moderately severe pain. When taken by mouth in an immediate-release formulation, the onset of pain relief usually begins within an hour. It is also available by injection. It is available in combination with paracetamol (acetaminophen). As is typical of opioids, common side effects include constipation, itchiness, and nausea. Serious side effects may include hallucinations, seizures, increased risk of serotonin syndrome, decreased alertness, and drug addiction. A change in dosage may be recommended in those with kidney or liver problems. It is not recommended in those who are at risk of suicide or in those who are pregnant. While not recommended in women who are breastfeeding, those who take a single dose should not generally stop breastfeeding. Tramadol is converted in the liver to O-desmethyltramadol (desmetramadol), an opioid with a stronger affinity to the μ-opioid receptor. Tramadol is also a serotonin–norepinephrine reuptake inhibitor (SNRI).Tramadol was patented in 1963 and launched under the name "Tramal" in 1977 by the West German pharmaceutical company Grünenthal GmbH. In the mid-1990s, it was approved in the United Kingdom and the United States. It is available as a generic medication and marketed under many brand names worldwide. In 2020, it was the 35th most commonly prescribed medication in the United States, with more than 17 million prescriptions. Medical uses
Tramadol (a schedule IV drug in the US) is used primarily to treat mild to severe pain, both acute and chronic.