title: Burn injury decreases the antinociceptive effects of opioids.
abstract: Burn victim patients are frequently prescribed opioids at doses that are significantly higher than standard analgesic dosing guidelines, and, even despite an escalation in opioid dosing, many continue to experience pain. Thus, the aim of this study was to determine the effect of burn injury on opioid antinociception. Mice were examined for their baseline pain sensitivity thresholds using the von Frey filaments test. Then, they were subjected to burn or sham injury to the dorsal surface of the hindpaw and treated orally with morphine, oxycodone, hydrocodone (20 or 40 mg/kg), or saline twice daily throughout the study. They were retested on days 4, 7, 11, 14, 21, and 28 following the burn injury. The antinociceptive effects of the various drugs were analyzed by computing the daily difference between pain sensitivity threshold scores (in g) before and after treatment. This study showed that burn injury decreases opioid antinociception potency. A marked reduction was observed in the antinociceptive effectiveness of all opioids, and for both doses, in the burn-injured versus the sham animals. These results suggest that burn trauma limits the ability of opioids to be effective in reducing pain.
authors.affiliation: aBehavioral and Cellular Neuroscience, Department of Psychology, Texas A&M University bInterdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), College Station, Texas, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Emery
authors.forename: M L Shawn
authors.initials: MLS
authors.lastname: Bates
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wellman
authors.forename: Shoshana
authors.initials: S
authors.lastname: Eitan
mesh_terms: D000284:Administration, Oral; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002056:Burns / Q000150:complications* / Q000473:pathology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006853:Hydrocodone / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology; D010098:Oxycodone / Q000008:administration & dosage / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy*; D017288:Pain Threshold / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D006853:Hydrocodone; D009020:Morphine; D010098:Oxycodone