Morphine-6-glucuronide, a potent mu agonist

Life Sci. 1987 Dec 28;41(26):2845-9. doi: 10.1016/0024-3205(87)90431-0.


The 3- and the 6-glucuronides of morphine have been examined in binding studies and in vivo. The 3-glucuronide had poor affinity in all binding studies whereas the 6-glucuronide potently labeled mu, but not delta or kappa receptors with affinities similar to morphine. Microinjections of the 3-glucuronide directly into the periaqueductal gray were without effect. The 6-glucuronide, on the other hand, was up to 20-fold more potent than morphine following microinjections in the same region. High doses of the 6-glucuronide produced profound seizure activity. All 6-glucuronide actions were sensitive to the opiate antagonist naloxone.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Biotransformation
  • Male
  • Microinjections
  • Morphine / metabolism
  • Morphine / pharmacology
  • Morphine Derivatives / metabolism
  • Morphine Derivatives / pharmacology*
  • Rats
  • Rats, Inbred Strains
  • Receptors, Opioid / metabolism*
  • Receptors, Opioid, delta
  • Receptors, Opioid, mu


  • Morphine Derivatives
  • Receptors, Opioid
  • Receptors, Opioid, delta
  • Receptors, Opioid, mu
  • morphine-6-glucuronide
  • Morphine
  • morphine-3-glucuronide