Naloxone displacement at opioid receptor sites measured in vivo in the human brain

Eur J Pharmacol. 2003 Jan 17;459(2-3):217-9. doi: 10.1016/s0014-2999(02)02872-8.


We report the use of a sensitive non-tomographic positron detecting system to measure the dose-response curve of naloxone in human brain. [11C]Diprenorphine was administered to normal volunteers in tracer amounts and, 30 min later, various bolus doses of naloxone were given (1.5-160 microg/kg) intravenously and change in [11C]diprenorphine binding monitored over the next 30 min. We found that this method produced results consistent with existing data. It was observed that approximately 13 microg/kg of naloxone ( approximately 1 mg in an 80 kg man) was required to produce an estimated 50% receptor occupation. This is consistent with the clinical dose of naloxone used to reverse opiate overdose (0.4 mg-1.2 mg).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites / physiology
  • Brain / metabolism*
  • Diprenorphine / metabolism
  • Dose-Response Relationship, Drug
  • Humans
  • Naloxone / metabolism*
  • Receptors, Opioid / metabolism*


  • Receptors, Opioid
  • Diprenorphine
  • Naloxone