Published: Journal of Analytical Toxicology, ISSN 0146-4760, Volume 25, Number 7, October, pp.538-549

Temporal Indication of Marijuana Use Can Be Estimated From Plasma and Urine Concentrations of D₉-Tetrahydrocannabinol, 11-Hydroxy-D₉-Tetrahydrocannabinol, and 11-Nor-D₉-Tetrahydrocannabinol-9-Carboxylic Acid
Joseph E. Manno[1],[2], Barbara R. Manno[2], Philip M. Kemp[3], Dempsey D. Alford[1], Imad K. Abukhalaf[2] Mary E. McWilliams[4], Frances N. Hagaman[2], and Mary Jo Fitzgerald[2]
Departments of Emergency Medicine (Section of Toxicology)[1], Psychiatry[2], and Neurology[4], Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130 and [3]Chief Medical Examiner’s Office, Oklahoma City, Oklahoma 73117

Current technology establishes marijuana use based upon detection of the pharmacologically inactive cannabinoid metabolite (11-nor-D₉-carboxy-tetrahydrocannabinol-9-carboxylic acid, THC-COOH) in urine. No accurate prediction of time of use is possible because THC-COOH has a half-life of 6 days. To determine if a temporal relationship between marijuana use and metabolite excretion patterns could be established, eight healthy user-volunteers (18–35 years old) smoked marijuana cigarettes containing 0% (placebo), 1.77%, and 3.58% D₉-tetrahydrocannabinol (THC). Plasma and urine were collected prior to smoking, 5 min after smoking, and hourly thereafter for 8 h for measurement of cannabinoid concentrations by gas chromatography–mass spectrometry. Mathematical models proposed for determination of recent marijuana use were applied to data from this study and verified the temporal use of marijuana. One subject, who later admitted chronic marijuana use (urine baseline THCCOOH, 529.2 ng/mL; plasma, 75.5 ng/mL), excreted 8b- dihydroxy-THC, peaking 2 h postsmoking (92.3 ng/mL). Urinary THC, the psychoactive component of marijuana, concentrations peaked 2 h after smoking and declined to assay limit of detection (LOD) (1.5 ng/mL) by 6 h. 11-Hydroxy-D₉-tetrahydrocannabinol (11-OH-THC) and THCCOOH were detectable for the entire 8-h testing period but continued to decrease. Urinary concentrations of THC greater than 1.5 ng/mL suggests marijuana use during the previous 8-h time period.

Reproduction of editorial content of this journal is prohibited without publisher’s permission.

| Home | Subscribe | Current Issue | Back Issues | Search | Advertise | Other Publications |