title: Urinary cannabinoid disposition in occasional and frequent smokers: is THC-glucuronide in sequential urine samples a marker of recent use in frequent smokers?
abstract: BACKGROUND
  There is extended urinary excretion of Δ(9)-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) in abstinent frequent cannabis smokers. We characterized THC, 11-OH-THC, THCCOOH, cannabidiol, cannabinol, THC-glucuronide, and THCCOOH-glucuronide disposition in urine of frequent and occasional cannabis smokers, and we propose a model to predict recent cannabis smoking.
  
  
  METHODS
  Frequent and occasional smokers resided on a closed research unit and smoked one 6.8% THC cannabis cigarette ad libitum. Urinary cannabinoids were quantified in each void by liquid chromatography-tandem mass spectrometry within 24 h of collection.
  
  
  RESULTS
  No urine samples had measureable THC, 11-OH-THC, cannabidiol, or cannabinol. THCCOOH, THC-glucuronide, and THCCOOH-glucuronide were measurable in all frequent smokers' urine and 60%, 100%, and 100% of occasional smokers' urine samples, respectively. Pre- and postdose maximal concentrations (non- and creatinine normalized) and probability of being positive were significantly higher in frequent smokers' samples. THC-glucuronide concentrations peaked 0.6-7.4 h after smoking; THCCOOH and THCCOOH-glucuronide concentrations were highly variable. At the newly adopted THCCOOH 175-μg/L World Anti-Doping Agency decision limit, only 50% of frequent smokers were positive 0-6 h postdose; no occasional smokers' samples were positive. An absolute %difference of ≥50% between 2 consecutive THC-glucuronide-positive samples with a creatinine-normalized concentration of ≥2 μg/g in the first sample predicted cannabis smoking with efficiencies of 93.1% in frequent and 76.9% in occasional smokers within 6 h of first sample collection.
  
  
  CONCLUSIONS
  These controlled urinary cannabinoid data provide a possible means of identifying recent cannabis intake in cannabis smokers' urine within a short collection time frame after smoking.
authors.affiliation: Chemistry and Drug Metabolism Section, NIDA IRP, Baltimore, MD;
authors.forename: Nathalie A
authors.initials: NA
authors.lastname: Desrosiers
authors.forename: Dayong
authors.initials: D
authors.lastname: Lee
authors.forename: Marta
authors.initials: M
authors.lastname: Concheiro-Guisan
authors.forename: Karl B
authors.initials: KB
authors.lastname: Scheidweiler
authors.forename: David A
authors.initials: DA
authors.lastname: Gorelick
authors.forename: Marilyn A
authors.initials: MA
authors.lastname: Huestis
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002186:Cannabinoids / Q000652:urine*; D005260:Female; D020719:Glucuronides / Q000652:urine*; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008385:Marijuana Smoking / Q000652:urine*; D008875:Middle Aged; D008954:Models, Biological; D011237:Predictive Value of Tests; D015813:Substance Abuse Detection / Q000379:methods*; D014018:Tissue Distribution; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002186:Cannabinoids; D020719:Glucuronides