title: [Antinociceptive effects of the combination metamizol + morphine in rats with intense pain (arthritic gout-type pain produced with AU)].
abstract: 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.
authors.affiliation: Departamento de Farmacobiología, Cinvestav-Sede Sur, México, D.F., Mexico.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Godínez-Chaparro
authors.forename: Uriah
authors.initials: U
authors.lastname: Guevara-López
authors.forename: Minarda
authors.initials: M
authors.lastname: de la O-Arciniega
authors.forename: Alma Rosa
authors.initials: AR
authors.lastname: Cortés-Arroyo
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: López-Muñoz
mesh_terms: 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
chemical_list: D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal; D014527:Uric Acid; D004177:Dipyrone; D009020:Morphine