Tramadol (marketed as the hydrochloride salt by Janssen Pharmaceutica as Ultram, and as generics) is used to treat moderate to moderately severe pain. It has two different mechanisms. First, it binds to the u-opioid receptor. Second, it inhibits the reuptake of serotonin and norepinephrine.
Tramadol is a centrally acting atypical opioid analgesic with additional serotonin-norepinephrine reuptake-inhibiting effects. It 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 as this is known to improve the efficacy of tramadol in relieving pain.
Tramadol is an atypical opioid because it is a serotonin-norepinephrine reuptake inhibitor of and, by itself, a fairly weak μ-opioid receptor agonist. Tramadol is metabolised to O-desmethyltramadol, which is a significantly more potent opioid with additional norepinephrine reuptake-inhibiting properties, making it analogous to tapentadol. When taken as an immediate-release oral formulation, the onset of pain relief usually occurs within about an hour.
Tramadol is used primarily to treat moderate-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.