Tapentadol (brand names: Nucynta, Palexia and Tapal) 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.