Tramadol acts on the central nervous system and unlike codeine and its derivative medications is a totally synthetic analgesic compound. Although its mode of action is not completely understood, from animal tests, at least two complementary mechanisms appear applicable: the binding of parent compound and its metabolite to opioid receptors and weak inhibition of reuptake of norepinephrine and serotonin by nerves located within the central nervous system. Tramadol-induced analgesia is only partially reversed by the opiate antagonist naloxone in several animal tests. Tramadol has been shown to inhibit reuptake of norepinephrine and serotonin in vitro. These mechanisms may contribute independently to the overall analgesic profile of Tramadol. Analgesia in humans begins approximately within one hour after administration and reaches a peak in approximately two to three hour