Chronic methadone treatment shows a better cost/benefit ratio than chronic morphine in mice

Johan Enquist, Madeline Ferwerda, Laura Milan-Lobo, Jennifer Whistler

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Chronic treatment of pain with opiate drugs can lead to analgesic tolerance and drug dependence. Although all opiate drugs can promote tolerance and dependence in practice, the severity of those unwanted side effects differs depending on the drug used. Although each opiate drug has its own unique set of pharmacological profiles, methadone is the only clinically used opioid drug that produces substantial receptor endocytosis at analgesic doses. Here, we examined whether moderate doses of methadone carry any benefits over chronic use of equianalgesic morphine, the prototypical opioid. Our data show that chronic administration of methadone produces significantly less analgesic tolerance than morphine. Furthermore, we found significantly reduced precipitated withdrawal symptoms after chronic methadone treatment than after chronic morphine treatment. Finally, using a novel animal model with a degrading μ-opioid receptor we showed that, although endocytosis seems to protect against tolerance development, endocytosis followed by receptor degradation produces a rapid onset of analgesic tolerance to methadone. Together, these data indicated that opioid drugs that promote receptor endocytosis and recycling, such as methadone, may be a better choice for chronic pain treatment than morphine and its derivatives that do not.

Original languageEnglish (US)
Pages (from-to)386-392
Number of pages7
JournalJournal of Pharmacology and Experimental Therapeutics
Issue number2
StatePublished - Feb 1 2012
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology


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