Is tapentadol a glorified tramadol?
Tapentadol is a mu-opioid agonist and also blocks reuptake of norepinephrine, the latter of which is particularly useful for the treatment of neuropathic pain. Additionally, tramadol blocks reuptake of serotonin; hence it is a serotonin norepinephrine reuptake inhibitor (SNRI) of sorts. Tramadol is metabolized by CYP 2D6 via O-demethylation to the active analgesic compound O -desmethyl-tramadol (M1). Tramadol also undergoes N-demethylation via CYP 3A4 and 2B6. M1 is more potent than its parent compound tramadol; however, M1 has difficulty penetrating the central nervous system. Comparatively, tapentadol does not require a CYP enzyme for analgesic activation. Tramadol requires renal and hepatic dosage adjustment, but there is no renal data currently published for tapentadol; however, the renal metabolite was found to be nonactive in preclinical trials. The mu-opioid binding affinity of tramadol at the receptor is 6000 times less than that of morphine compared to tapentadol, whose binding affinity at that same receptor is 18 times less than that of morphine.