Effects of tramadol on experimental inflammation

We examined the ability of the analgesic drug tramadol to affect the develo pment of inflammation in rats. The acute administration of tramadol signifi cantly reduced the edema and the hyperalgesia induced by yeast injection in the paw. Moreover, in the subcutaneous carrageenin-induced inflammation, t ramadol reduced the amount of the exudate, as well as the prostaglandin (PG )E-2-like bio- and immunoactivity in the exudate; on the contrary, leukotri ene (LT)B-4 concentrations in the exudate were not changed. However, tramad ol did not affect the ability of macrophages to migrate towards the chemota ctic peptide N-formyl-L-methionil-L-leucyl-L-phenylalanine (FMLP). Our resu lts suggest that tramadol is able to inhibit the development of different t ypes of inflammation in the rat without affecting immune mechanisms, and co ntribute to explain the efficacy of this drug in the treatment of inflammat ory pain. (C) Elsevier, Paris.