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Predictive model accuracy in estimating last Δ9-tetrahydrocannabinol (THC) intake from plasma and whole blood cannabinoid concentrations in chronic, daily cannabis smokers administered subchronic oral THC.
Drug Alcohol Depend. 2012 Oct 01; 125(3):313-9.DA

Abstract

BACKGROUND

Determining time since last cannabis/Δ9-tetrahydrocannabinol (THC) exposure is important in clinical, workplace, and forensic settings. Mathematical models calculating time of last exposure from whole blood concentrations typically employ a theoretical 0.5 whole blood-to-plasma (WB/P) ratio. No studies previously evaluated predictive models utilizing empirically-derived WB/P ratios, or whole blood cannabinoid pharmacokinetics after subchronic THC dosing.

METHODS

Ten male chronic, daily cannabis smokers received escalating around-the-clock oral THC (40-120 mg daily) for 8 days. Cannabinoids were quantified in whole blood and plasma by two-dimensional gas chromatography-mass spectrometry.

RESULTS

Maximum whole blood THC occurred 3.0 h after the first oral THC dose and 103.5h (4.3 days) during multiple THC dosing. Median WB/P ratios were THC 0.63 (n=196), 11-hydroxy-THC 0.60 (n=189), and 11-nor-9-carboxy-THC (THCCOOH) 0.55 (n=200). Predictive models utilizing these WB/P ratios accurately estimated last cannabis exposure in 96% and 100% of specimens collected within 1-5h after a single oral THC dose and throughout multiple dosing, respectively. Models were only 60% and 12.5% accurate 12.5 and 22.5h after the last THC dose, respectively.

CONCLUSIONS

Predictive models estimating time since last cannabis intake from whole blood and plasma cannabinoid concentrations were inaccurate during abstinence, but highly accurate during active THC dosing. THC redistribution from large cannabinoid body stores and high circulating THCCOOH concentrations create different pharmacokinetic profiles than those in less than daily cannabis smokers that were used to derive the models. Thus, the models do not accurately predict time of last THC intake in individuals consuming THC daily.

Authors+Show Affiliations

Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, N.I.H., Intramural

Language

eng

PubMed ID

22464363

Citation

Karschner, Erin L., et al. "Predictive Model Accuracy in Estimating Last Δ9-tetrahydrocannabinol (THC) Intake From Plasma and Whole Blood Cannabinoid Concentrations in Chronic, Daily Cannabis Smokers Administered Subchronic Oral THC." Drug and Alcohol Dependence, vol. 125, no. 3, 2012, pp. 313-9.
Karschner EL, Schwope DM, Schwilke EW, et al. Predictive model accuracy in estimating last Δ9-tetrahydrocannabinol (THC) intake from plasma and whole blood cannabinoid concentrations in chronic, daily cannabis smokers administered subchronic oral THC. Drug Alcohol Depend. 2012;125(3):313-9.
Karschner, E. L., Schwope, D. M., Schwilke, E. W., Goodwin, R. S., Kelly, D. L., Gorelick, D. A., & Huestis, M. A. (2012). Predictive model accuracy in estimating last Δ9-tetrahydrocannabinol (THC) intake from plasma and whole blood cannabinoid concentrations in chronic, daily cannabis smokers administered subchronic oral THC. Drug and Alcohol Dependence, 125(3), 313-9. https://doi.org/10.1016/j.drugalcdep.2012.03.005
Karschner EL, et al. Predictive Model Accuracy in Estimating Last Δ9-tetrahydrocannabinol (THC) Intake From Plasma and Whole Blood Cannabinoid Concentrations in Chronic, Daily Cannabis Smokers Administered Subchronic Oral THC. Drug Alcohol Depend. 2012 Oct 1;125(3):313-9. PubMed PMID: 22464363.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Predictive model accuracy in estimating last Δ9-tetrahydrocannabinol (THC) intake from plasma and whole blood cannabinoid concentrations in chronic, daily cannabis smokers administered subchronic oral THC. AU - Karschner,Erin L, AU - Schwope,David M, AU - Schwilke,Eugene W, AU - Goodwin,Robert S, AU - Kelly,Deanna L, AU - Gorelick,David A, AU - Huestis,Marilyn A, Y1 - 2012/03/29/ PY - 2011/11/12/received PY - 2012/01/29/revised PY - 2012/03/04/accepted PY - 2012/4/3/entrez PY - 2012/4/3/pubmed PY - 2013/2/13/medline SP - 313 EP - 9 JF - Drug and alcohol dependence JO - Drug Alcohol Depend VL - 125 IS - 3 N2 - BACKGROUND: Determining time since last cannabis/Δ9-tetrahydrocannabinol (THC) exposure is important in clinical, workplace, and forensic settings. Mathematical models calculating time of last exposure from whole blood concentrations typically employ a theoretical 0.5 whole blood-to-plasma (WB/P) ratio. No studies previously evaluated predictive models utilizing empirically-derived WB/P ratios, or whole blood cannabinoid pharmacokinetics after subchronic THC dosing. METHODS: Ten male chronic, daily cannabis smokers received escalating around-the-clock oral THC (40-120 mg daily) for 8 days. Cannabinoids were quantified in whole blood and plasma by two-dimensional gas chromatography-mass spectrometry. RESULTS: Maximum whole blood THC occurred 3.0 h after the first oral THC dose and 103.5h (4.3 days) during multiple THC dosing. Median WB/P ratios were THC 0.63 (n=196), 11-hydroxy-THC 0.60 (n=189), and 11-nor-9-carboxy-THC (THCCOOH) 0.55 (n=200). Predictive models utilizing these WB/P ratios accurately estimated last cannabis exposure in 96% and 100% of specimens collected within 1-5h after a single oral THC dose and throughout multiple dosing, respectively. Models were only 60% and 12.5% accurate 12.5 and 22.5h after the last THC dose, respectively. CONCLUSIONS: Predictive models estimating time since last cannabis intake from whole blood and plasma cannabinoid concentrations were inaccurate during abstinence, but highly accurate during active THC dosing. THC redistribution from large cannabinoid body stores and high circulating THCCOOH concentrations create different pharmacokinetic profiles than those in less than daily cannabis smokers that were used to derive the models. Thus, the models do not accurately predict time of last THC intake in individuals consuming THC daily. SN - 1879-0046 UR - https://www.unboundmedicine.com/medline/citation/22464363/Predictive_model_accuracy_in_estimating_last_Δ9_tetrahydrocannabinol__THC__intake_from_plasma_and_whole_blood_cannabinoid_concentrations_in_chronic_daily_cannabis_smokers_administered_subchronic_oral_THC_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0376-8716(12)00079-8 DB - PRIME DP - Unbound Medicine ER -