THE PHARMACOLOGY OF TRAMADOL

(+/-)-Tramadol is a central analgesic with low affinity for opioid rec eptors. The rate of production of its M1 metabolite (O-demethyl tramad ol) is influenced by debrisoquine-type polymorphism, and this metaboli te shows a higher affinity for opioid receptors than the parent drug. Experimental and clinical data suggest that tramadol may also exert it s analgesic effect through direct modulation of central monoaminergic pathways. Indeed, after a single oral dose, the role of the mu-recepto r agonist component of the antinociceptive effect of tramadol appears to be minor, with most of the analgesic effect bring attributable to n onopioid properties of the parent compound. Approximately 2-fold accum ulation of the parent compound and the M1 metabolite may be expected d uring multiple dose treatment. The duration of analgesic effect after a single oral dose of tramadol 100mg is about 6 hours. Clinical experi ence has confirmed that tramadol is an effective and relatively safe a nalgesic that may be of value in several pain conditions not requiring treatment with strong opioids.