Analgesic effects of peripherally administered opioids in clinical models of acute and chronic inflammation

Clin Pharmacol Ther. 2001 Jul;70(1):66-73. doi: 10.1067/mcp.2001.116443.


A series of double-blind, placebo-controlled clinical trials demonstrated that low doses of morphine (0.4, 1.2, and 3.6 mg) administered into the intraligamentary space of a chronically inflamed hyperalgesic tooth produced a dose-related naloxone-reversible analgesia. This analgesic effect is mediated by a local mechanism in the inflamed tissue, because subcutaneous administration of a 1.2 mg dose of morphine failed to elicit an analgesic response. In contrast, submucosal administration of 1.2 mg morphine or 50 microg fentanyl to the site of extraction of an impacted third molar after the onset of acute pain failed to elicit an analgesic response despite demonstration of a sensitive bioassay. These data indicate that peripheral opioid analgesia can be evoked in a model of chronic, but not acute, inflammatory pain, suggesting a temporal dependent mechanism needed for the expression of peripheral opiate analgesia during inflammation in humans.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Acute Disease
  • Adult
  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / pharmacology*
  • Chronic Disease
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Female
  • Fentanyl / pharmacology
  • Humans
  • Injections
  • Male
  • Mepivacaine / pharmacology
  • Morphine / pharmacology
  • Naloxone / pharmacology
  • Pain Measurement
  • Pain, Postoperative / drug therapy*
  • Pain, Postoperative / etiology
  • Periodontitis / complications*
  • Time Factors
  • Tooth Extraction / adverse effects*
  • Toothache / drug therapy*
  • Toothache / etiology
  • Treatment Outcome


  • Analgesics, Opioid
  • Naloxone
  • Morphine
  • Mepivacaine
  • Fentanyl