Paracetamol exerts a spinal, tropisetron-reversible, antinociceptive effect in an inflammatory pain model in rats.
Experiments were performed in carrageenin-treated rats to study, the antinociceptive and anti-inflammatory effects of paracetamol intravenously (i.v.) or intrathecally (i.t.) injected on rats submitted to a mechanical noxious stimulus. The influence of intrathecal tropisetron, a 5 hydroxytryptamine(3) (5-HT(3)) receptor antagonist, on the antinociceptive effects of paracetamol, was also studied. Paracetamol induced a significant antinociceptive effect after (100, 200 and 300 mg/kg) i.v. and (50, 100 and 200 microg/rat) i.t. injection, but no change occurred on edema volume. The effect of paracetamol was totally inhibited by tropisetron (10 microg/rat, i.t.). The foregoing results demonstrate that, in conditions of inflammatory pain, paracetamol exerts a central antinociceptive effect involving spinal 5-HT(3) receptors, without inducing any anti-inflammatory action. These data, give further arguments to consider paracetamol as a central analgesic drug which must be distinguished from non-steroidal anti-inflammatory drugs (NSAIDs), which justifies the usual combination of paracetamol in post-operative pain.
Alloui
Abdelkrim
A
EMI INSERM/UdA 9904, Laboratoire de Pharmacologie Médicale, Faculté de Médecine, BP 38, 63001 Cedex 1, Clermont-Ferrand, France. abdelkrim.alloui@u-clermontl.fr
Chassaing
Claude
C
Schmidt
Jeannot
J
Ardid
Denis
D
Dubray
Claude
C
Cloarec
Alix
A
Eschalier
Alain
A
D000082:Acetaminophen / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004347:Drug Interactions; D004487:Edema / Q000139:chemically induced / Q000473:pathology; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007249:Inflammation / Q000188:drug therapy; D007275:Injections, Intravenous; D007278:Injections, Spinal; D008297:Male; D010146:Pain / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects*; D044406:Receptors, Serotonin, 5-HT3; D000077526:Tropisetron
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007211:Indoles; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D000082:Acetaminophen; D000077526:Tropisetron