Comparative pharmacology of Delta9-tetrahydrocannabinol and its metabolite, 11-OH-Delta9-tetrahydrocannabinol

J Clin Invest. 1973 Oct;52(10):2411-7. doi: 10.1172/JCI107431.


A comparison of the psychologic and physiologic effects of intravenously administered Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and 11-hydroxy-Delta(9)-tetrahydrocannabinol (11-OH-Delta(9)-THC) was carried out in nine casual marihuana smokers. A marked tachycardia and psychologic "high" occurred within 3-5 min after the i.v. administration of 11-OH-Delta(9)-THC (1 mg) to all subjects. In contrast, the peak psychologic "high" was delayed 10-20 min after the i.v. administration of Delta(9)-THC (1 mg). There was some individual variation in response among subjects. Psychologic effects correlated well with plasma levels of unchanged [(3)H]11-OH-Delta(9)-THC. About 75% of the administered radioactive dose was excreted in urine (25%) and feces (50%) after [(3)H]11-OH-Delta(9)-THC administration. The disposition, excretion, and metabolism of [(3)H]11-OH-Delta(9)-THC appear to be similar to that previously reported after [(14)C]Delta(9)-THC administration. These findings, in conjunction with the marked psychologic high seen after 11-OH-Delta(9)-THC, suggest that in man, Delta(9)-THC, the active constituent in marihuana, is converted to 11-OH-Delta(9)-THC, which is in part responsible for the psychologic effects.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Cannabis / pharmacology*
  • Dronabinol / administration & dosage
  • Dronabinol / analysis
  • Dronabinol / blood
  • Dronabinol / metabolism
  • Dronabinol / pharmacology
  • Dronabinol / urine
  • Ethanol / pharmacology
  • Euphoria / drug effects
  • Feces / analysis
  • Heart Rate / drug effects
  • Humans
  • Infusions, Parenteral
  • Male
  • Time Factors
  • Tritium


  • Tritium
  • Ethanol
  • Dronabinol