Temporal Indication of Marijuana Use Can Be Estimated From Plasma and Urine Concentrations of  9-Tetrahydrocannabinol, 11-Hydroxy- 9-Tetrahydrocannabinol, and 11-Nor- 9-Tetrahydrocannabinol-9-Carboxylic Acid

Abstract

Current technology establishes marijuana use based upon detection of the pharmacologically inactive cannabinoid metabolite (11-nor-delta9-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% delta9-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 8beta-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-delta9-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.

Comparison of Cannabinoid Concentrations in Plasma, Oral Fluid and Urine in Occasional Cannabis Smokers After Smoking Cannabis Cigarette

“…As demonstrated by Huestis et al [25], the THC-COOH plasma concentrations peaked later, and showed a long-lasting plateau followed by a slow decrease. The urinary peak times of THC and metabolites were in agreement with those found in a different study, involving smoking cannabis cigarettes which contained 3.58% THC [26].…”

“…No consistent THCCOOH/THC ratio pattern was evident. As reported previously [26], THC-COOH showed the highest intra-and inter-ubject variability and was still detectable after 4 days as the result of a 3.58% cannabis cigarette smoked [41]. Thus, the main THC metabolite is not suitable as a urine marker for recent use.…”

“…Thus, the main THC metabolite is not suitable as a urine marker for recent use. Instead, THC-COOH in urine is only suggestive of cannabis consumption at some time in the past [26].…”

“…These data are in close agreement with those reported by Huestis et al [35] who observed similar THC-COOH excretion percentages, 0.54 +/-0.1 and 0.53 +/-0.1%, of total dose following smoking of low and high-dose marijuana cigarettes. Manno et al [26] showed in eight occasional consumers a peak urinary excretion of 21.5μg/L, 77.3μg/L, 179 μg/L for THC, 11-OH-THC and THC-COOH at two, three and four h after smoking a cigarette containing 27mg of THC, respectively. These results are consistent with our values for a dose of 20mg despite slightly lower Tmax.…”

Medical Marijuana and Driving: a Review

“…Unfortunately, the rapid rise and decline in serum THC make it difficult to use as a marker of intoxication in the setting of real world driving. Serum must be drawn within 2 h of smoking marijuana to have a generally quantifiable concentration of THC; the psychomotor effects of marijuana, however, may exceed this time frame [43,44]. Whereas an undetectable blood alcohol concentration would effectively rule out driving under the influence of alcohol (barring the effects from a hangover), an undetectable THC concentration does not similarly rule out impairment.…”