[Recent evidences in the pharmacological mechanisms of the tramadol].
Tramadol [(1R, 2R) and (1S, 2S)-2-dimethyl-amino-methyl-1-(3-methoxyphenyl) -cyclohexanol hydrochloride] has been used clinically. It binds to micro-opioid receptors with lower affinity than morphine, which suggests that the antinociceptive action of tramadol may not be due to opioid receptor binding. Several lines of evidence have shown that tramadol inhibits the reuptake of monoamines, as do antidepressant drugs such as desipramine. Tramadol inhibits the reuptake of NE and serotonin. The mechanisms of action of tramadol have not been well understood. Recently, some evidences in the mechanisms of action of tramadol have been published. Tramadol inhibits the muscarinic receptor, serotonin receptor, and nicotinic acetylcholine receptor ion-channel, suggesting these receptors might be related to the mechanisms of action of tramadol. In this review, the mechanisms of action of tramadol were reviewed form these findings. Tramadol does not alter renal blood flow (RBF) in normal rats. This suggests that tramadol would be a safe analgesic maintaining RBF during the postoperative period. It would be necessary to study the effects of tramadol on orphan G-ptotein coupled receptor which is related to the pain.
Mimami
Kouichiro
K
Department of Anesthesiology, University of Occupational and Environmental Health, Kitakyushu 807 8555.
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D006801:Humans; D007473:Ion Channels / Q000187:drug effects; D009294:Narcotics / Q000494:pharmacology*; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000187:drug effects; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects; D011968:Receptors, Histamine / Q000528:radiation effects; D011976:Receptors, Muscarinic / Q000187:drug effects; D014147:Tramadol / Q000378:metabolism / Q000494:pharmacology*
D000701:Analgesics, Opioid; D007473:Ion Channels; D009294:Narcotics; D050484:Norepinephrine Plasma Membrane Transport Proteins; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D011976:Receptors, Muscarinic; D014147:Tramadol