Tramadol is a centrally acting synthetic opioid analgesic commonly prescribed for moderate to severe pain. Its increasing use may be related to the fact that it has fewer side effects than other opioids, in particular, less addictive potential and less respiratory depression.Tramadol was the second most frequent opioid reported (Bamigbade et al., 1998).
Tramadol is a synthetic analog of codeine with both opioid and monoamine reuptake inhibitory effects. Analgesia results from its weak agonist action on mu- receptors and also from its inhibition of the reuptake of norepinephrine , serotonin and endogenous neurotransmitters that modulate pain (Kleinschmidt et al., 2001).
Numerous clinical trials have proven its efficacy and safety over a broad range of painful conditions, both acute and chronic; however, in severe pain, morphine may be superior to tramadol (Houmes et al., 1992).
Tramadol has a dose-dependent efficacy that lies between that of codeine and morphine, with a parenteral potency about 10-20% of morphine (Vickers, 1992).
Tramadol could be effective for alleviating symptoms of depression, anxiety and phobias.This effect is due to its action on the noradrenergic and serotonergic systems that known as its atypical opioid activity (Rojas-Corrales et al., 2004)
Higher doses of tramadol can be associated with cardiovascular collapse, coma, seizures and respiratory depression (Chandrasekaran et al., 2007).