Urinary excretion half-life of delta 1-tetrahydrocannabinol-7-oic acid in heavy marijuana users after smoking

J Anal Toxicol. Jul-Aug 1989;13(4):218-23. doi: 10.1093/jat/13.4.218.


The urinary excretion of the total amount of delta 1-tetrahydrocannabinol (delta 1-THC) metabolites, with special emphasis on delta 1-tetrahydrocannabinol-7-oic acid (delta 1-THC-7-oic acid), was studied in thirteen heavy Cannabis users after smoking administration of delta 1-THC, followed by a four week discontinuation period. The total amount of delta 1-THC metabolites and the levels of delta 1-THC-7-oic acid could be followed up to 25 days after abstinence using EMIT d.a.u. cannabinoid assay and high-performance liquid chromatography (HPLC). The urinary excretion half-life, calculated from the concentrations of delta 1-THC-7-oic acid versus time, ranged from 0.8-9.8 days with a mean (+/- SD) of 3.0 +/- 2.3 days. Most of the delta 1-THC-7-oic acid was excreted as conjugate and only trace amounts of unconjugated delta 1-THC-7-oic acid were detected. The total concentrations of delta 1-THC-7-oic acid in urine were compared to the concentrations of "cross-reacting cannabinoids", within the linear range of 20-75 ng/mL, obtained in the semiquantitative EMIT d.a.u. cannabinoid assay. The average ratio of "EMIT concentrations"/delta 1-THC-7-oic acid concentrations obtained by HPLC analysis was 1.23 +/- 84% (C.V.) for 78 urine samples. A total of 83% of the samples with positive EMIT levels (cutoff 20 ng/mL) was confirmed by HPLC analysis (cutoff 7 ng/mL).

Publication types

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

MeSH terms

  • Cannabinoids / urine
  • Dronabinol / administration & dosage
  • Dronabinol / analogs & derivatives*
  • Dronabinol / blood
  • Dronabinol / metabolism*
  • Dronabinol / pharmacokinetics
  • Dronabinol / urine
  • Humans
  • Male
  • Marijuana Smoking / metabolism
  • Marijuana Smoking / urine*


  • Cannabinoids
  • delta(6)-tetrahydrocannabinol-7-oic acid
  • Dronabinol