Tapentadol

Tapentadol, brand names Nucynta among others, is a centrally acting opioid analgesic of the benzenoid class with a dual mode of action as an agonist of the μ-opioid receptor and as a norepinephrine reuptake inhibitor (NRI). Analgesia occurs within 32 minutes of oral administration, and lasts for 4–6 hours. Tapentadol, brand names Nucynta among others, is a centrally acting opioid analgesic of the benzenoid class with a dual mode of action as an agonist of the μ-opioid receptor and as a norepinephrine reuptake inhibitor (NRI). Analgesia occurs within 32 minutes of oral administration, and lasts for 4–6 hours. It is similar to tramadol in its dual mechanism of action; namely, its ability to activate the mu opioid receptor and inhibit the reuptake of norepinephrine. Unlike tramadol, it has only weak effects on the reuptake of serotonin and is a significantly more potent opioid with no known active metabolites. Tapentadol is not a pro-drug and therefore does not rely on metabolism to produce its therapeutic effects; this makes it a useful moderate-potency analgesic option for patients who do not respond adequately to more commonly used opioids due to genetic disposition (poor metabolizers of CYP3A4 and CYP2D6), as well as providing a more consistent dosage-response range among the patient population. The potency of Tapentadol is somewhere between that of tramadol and morphine, with an analgesic efficacy comparable to that of oxycodone despite a lower incidence of side effects. It is generally regarded as a weak-moderate strength opioid (a category shared by many better-known opioids such as hydrocodone and pethidine). Tapentadol was approved by the US FDA in November 2008, by the TGA of Australia in December 2010 and by the MHRA of the UK in February 2011. Tapentadol is used for the treatment of moderate to severe pain for both acute (following injury, surgery, etc.) and chronic musculoskeletal pain. It is also specifically indicated for controlling the pain of diabetic neuropathy when around-the-clock opioid medication is required. Its general potency is somewhere between that of tramadol and morphine, with an analgesic efficacy comparable to that of oxycodone despite a lower incidence of side effects. Tapentadol is Pregnancy Category C. There are no adequate and well-controlled studies of tapentadol in pregnant women, and tapentadol is not recommended for use in women during and immediately prior to labor and delivery. There are no adequate and well-controlled studies of tapentadol in children. Tapentadol is contraindicated in people with epilepsy or who are otherwise prone to seizures. It raises intracranial pressure so should not be used in people with head injuries, brain tumors, or other conditions which increase intracranial pressure. It increases the risk of respiratory depression so should not be used in people with asthma. As with other mu-opioid agonists, tapentadol may cause spasms of the sphincter of Oddi, and is therefore discouraged for use in patients with biliary tract disease such as both acute and chronic pancreatitis. People who are rapid or ultra rapid metabolizers for the CYP2C9, CYP2C19, and CYP2D6 enzymes may not respond adequately to tapentadol therapy. Due to reduced clearance, tapentadol should be administered with caution to people with moderate liver disease and not at all in people with severe liver disease.