THCCOOH concentrations in whole blood: Are they useful in discriminating occasional from heavy smokers?

Authors

  • Marie Fabritius,

    1. CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland
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  • Bernard Favrat,

    1. CURML (University Center of Legal Medicine), UMPT (Unit of Psychology and Traffic Medicine), Lausanne and Geneva, Switzerland
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  • Haithem Chtioui,

    1. Division of Clinical Pharmacology and Toxicology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Giovanni Battistella,

    1. Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Jean-Marie Annoni,

    1. Neurology Unit, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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  • Monique Appenzeller,

    1. Division of Clinical Pharmacology and Toxicology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Kim Dao,

    1. Division of Clinical Pharmacology and Toxicology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Eleonora Fornari,

    1. Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
    2. CIBM (Centre d'imagerie BioMédicale), Centre Hospitalier Universitaire Vaudois (CHUV) unit, Lausanne, Switzerland
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  • Estelle Lauer,

    1. CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland
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  • Jean-Frédéric Mall,

    1. Department of Psychiatry, SUPAA (Service Universitaire de Psychiatrie de l'Age Avancé), Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Philippe Maeder,

    1. Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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  • Patrice Mangin,

    1. CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland
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  • Christian Staub,

    1. CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland
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  • Christian Giroud

    Corresponding author
    1. CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland
    • Correspondence to: Christian Giroud, CURML (University Center of Legal Medicine), UTCF (Forensic Toxicology and Chemistry Unit), Lausanne and Geneva, Switzerland. E-mail: christian.giroud@chuv.ch

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Abstract

Some forensic and clinical circumstances require knowledge of the frequency of drug use. Care of the patient, administrative, and legal consequences will be different if the subject is a regular or an occasional cannabis smoker. To this end, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) has been proposed as a criterion to help to distinguish between these two groups of users. However, to date this indicator has not been adequately assessed under experimental conditions. We carried out a controlled administration study of smoked cannabis with a placebo. Cannabinoid levels were determined in whole blood using tandem mass spectrometry. Significantly high differences in THCCOOH concentrations were found between the two groups when measured during the screening visit, prior to the smoking session, and throughout the day of the experiment. Receiver operating characteristic (ROC) curves were determined and two threshold criteria were proposed in order to distinguish between these groups: a free THCCOOH concentration below 3 µg/L suggested an occasional consumption (≤ 1 joint/week) while a concentration higher than 40 µg/L corresponded to a heavy use (≥ 10 joints/month). These thresholds were tested and found to be consistent with previously published experimental data. The decision threshold of 40 µg/L could be a cut-off for possible disqualification for driving while under the influence of cannabis. A further medical assessment and follow-up would be necessary for the reissuing of a driving license once abstinence from cannabis has been demonstrated. A THCCOOH level below 3 µg/L would indicate that no medical assessment is required. Copyright © 2013 John Wiley & Sons, Ltd.

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