title: Muscle rigidity induced by the opioid analgesic tramadol, but not by the non-opioid flupirtine.
abstract: The influence of high doses of two analgesic drugs, tramadol and flupirtine on the electromyographic activity in the gastrocnemius soleus muscles was examined. Tramadol (100-200 mg/kg po) dose-dependently induced a tonic electromyographic activity, which is generally accepted as a model of the opiate-induced muscle rigidity. That effect was antagonized by intraperitoneal injection of naloxone (0.8 mg/kg ip). On the other hand, flupirtine even in the high doses (100-200 mg/kg po) did not induce any tonic electromyographic activity. The obtained results confirm an opiate-like action of tramadol, but not that of flupirtine, on the muscle tension.
authors.affiliation: Department of Neuro-Psychopharmacology, Polish Academy of Sciences, Kraków.
authors.forename: K
authors.initials: K
authors.lastname: Ossowska
authors.forename: S
authors.initials: S
authors.lastname: Wolfarth
mesh_terms: D000284:Administration, Oral; D000631:Aminopyridines / Q000494:pharmacology*; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D007274:Injections, Intraperitoneal; D008297:Male; D009127:Muscle Rigidity / Q000139:chemically induced*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014147:Tramadol / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D000631:Aminopyridines; D000700:Analgesics; D009270:Naloxone; D014147:Tramadol; C034161:flupirtine