Evidence for analgesia mediated by peripheral opioid receptors in inflamed synovial tissue

A. J. Lawrence, G. P. Joshi, A. Michalkiewiczi, W. P. Blunnie, D. C. Moriarty

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Intra-articular morphine (5 mg in 25 ml) was administered to patients for post-operative analgesia following arthroscopic knee surgery. At various time intervals, 30 min to 4 h post morphine, venous blood samples were taken in order to determine plasma levels of morphine and its primary metabolites, morphine-3-glucuronide and morphine-6-glucuronide. Measurable amounts of morphine and morphine-3-glucuronide were found in the plasma of 7/10 patients whereas morphine-6-glucuronide was detected in only 2/10 patients. The plasma levels of morphine were lower than that regarded sufficient for post-operative analgesia in all but two patients, indicating a possibility of peripheral analgesia. [p]In addition, synovial biopsy samples were assayed for the presence of opioid binding sites. Tissue samples from 11 different patients were analysed and 6/11 exhibited specific binding of [3H]naloxone, indicating the presence of opioid binding sites/receptors. The receptor type (i. e. μ, δ- or k-) is at present unknown. [p]Taken together, these data provide evidence that locally administered opiates can act on specific opioid receptors in the synovium to mediate analgesia.

Original languageEnglish (US)
Pages (from-to)351-355
Number of pages5
JournalEuropean Journal of Clinical Pharmacology
Issue number4
StatePublished - Oct 1 1992


  • Analgesia
  • Opioids
  • inflammation
  • peripheral
  • receptors

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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