[Antinociceptive effects of the combination metamizol + morphine in rats with intense pain (arthritic gout-type pain produced with AU)].
BACKGROUND
The antinociceptive effects of metamizol and morphine administered either separately or in combination were determined in the "Pain-Induced Functional Impairment Model in the Rat" (PIFIR antinociceptive model).


METHODS
Intense nociception (or intense pain) was induced by the intra-articular injection of uric acid (50%) in the right hind limb inducing its dysfunction. Animals then received analgesic agents, and the recovery of functionality over time was assessed as an expression of antinociception.


RESULTS
Metamizol (177.8 mg/kg s.c.) or morphine (3.2 mg/kg s.c.) separately resulted in a lower antinociceptive effect (22.1+/-5.4 area units [au] and 31.8+/-9.4 au, respectively). Moreover, the combination of metamizol (177.8 mg/kg) with morphine (3.2 mg/kg) resulted in a potentiation (293.7+/-16.6 au). The antinociceptive effect observed using the combination was significantly greater than expected on the basis of addition of the individual effects. The percent change in antinociceptive effects, using the combination, was 444.9%.


CONCLUSIONS
This represents the first study to show that metamizol + morphine can produce potentiation of their antinociceptive effects in intense pain.
Godínez-Chaparro
Beatriz
B
Departamento de Farmacobiología, Cinvestav-Sede Sur, México, D.F., Mexico.
Guevara-López
Uriah
U
de la O-Arciniega
Minarda
M
Cortés-Arroyo
Alma Rosa
AR
López-Muñoz
Francisco Javier
FJ
D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D015210:Arthritis, Gouty; D004177:Dipyrone / Q000008:administration & dosage*; D004359:Drug Therapy, Combination; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D010146:Pain / Q000188:drug therapy*; D051381:Rats; D017208:Rats, Wistar; D012720:Severity of Illness Index; D014527:Uric Acid / Q000008:administration & dosage
D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal; D014527:Uric Acid; D004177:Dipyrone; D009020:Morphine