Effects of dextromethorphan and oxycodone on treatment of neuropathic pain in mice

Pao Pao Yang, Geng Chang Yeh, Eagle Yi Kung Huang, Ping Yee Law, Horace H. Loh, Pao Luh Tao

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Background: Neuropathic pain is a very troublesome and difficult pain to treat. Although opioids are the best analgesics for cancer and surgical pain in clinic, only oxycodone among opioids shows better efficacy to alleviate neuropathic pain. However, many side effects associated with the use of oxycodone render the continued use of it in neuropathic pain treatment undesirable. Hence, we explored whether dextromethorphan (DM, a known N-methyl-D-aspartate receptor antagonist with neuroprotective properties) could potentiate the anti-allodynic effect of oxycodone and underlying mechanisms regarding to glial cells (astrocytes and microglia) activation and proinflammatory cytokines release in a spinal nerve injury (SNL) mice model. Results: Oxycodone produced a dose-dependent anti-allodynic effect. Co-administration of DM at a dose of 10 mg/kg (i.p.) (DM10) which had no anti-allodynic effect by itself enhanced the acute oxycodone (1 mg/kg, s.c.) effect. When the chronic anti-allodynic effects were examined, co-administration of DM10 also significantly enhanced the oxycodone effect at 3 mg/kg. Furthermore, oxycodone decreased SNL-induced activation of glial cells (astrocytes and microglia) and plasma levels of proinflammatory cytokines (IL-6, IL-1β and TNF-α). Co-administration of DM10 potentiated these effects of oxycodone. Conclusion: The combined use of DM with oxycodone may have therapeutic potential for decreasing the effective dose of oxycodone on the treatment of neuropathic pain. Attenuation of the glial activation and proinflammatory cytokines in the spinal cord may be important mechanisms for these effects of DM.

Original languageEnglish (US)
Article number81
JournalJournal of biomedical science
Issue number1
StatePublished - Sep 22 2015

Bibliographical note

Funding Information:
This work was supported by a grant from the National Science Council (NSC 100-2320-B-400-002-MY3), Taipei, Taiwan, ROC. We are grateful to Mr. M. Swofford for English editing of the paper.

Publisher Copyright:
© 2015 Yang et al.


  • Allodynia
  • Dextromethorphan
  • Neuropathic pain
  • Oxycodone
  • Spinal nerve ligation


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