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Do Delta9-tetrahydrocannabinol concentrations indicate recent use in chronic cannabis users?

Abstract

AIMS

To quantify blood Delta(9)-tetrahydrocannabinol (THC) concentrations in chronic cannabis users over 7 days of continuous monitored abstinence.

PARTICIPANTS

Twenty-five frequent, long-term cannabis users resided on a secure clinical research unit at the US National Institute on Drug Abuse under continuous medical surveillance to prevent cannabis self-administration.

MEASUREMENTS

Whole blood cannabinoid concentrations were determined by two-dimensional gas chromatography-mass spectrometry.

FINDINGS

Nine chronic users (36%) had no measurable THC during 7 days of cannabis abstinence; 16 had at least one positive THC > or =0.25 ng/ml, but not necessarily on the first day. On day 7, 6 full days after entering the unit, six participants still displayed detectable THC concentrations [mean +/- standard deviation (SD), 0.3 +/- 0.7 ng/ml] and all 25 had measurable carboxy-metabolite (6.2 +/- 8.8 ng/ml). The highest observed THC concentrations on admission (day 1) and day 7 were 7.0 and 3.0 ng/ml, respectively. Interestingly, five participants, all female, had THC-positive whole blood specimens over all 7 days. Body mass index did not correlate with time until the last THC-positive specimen (n = 16; r = -0.2; P = 0.445).

CONCLUSIONS

Substantial whole blood THC concentrations persist multiple days after drug discontinuation in heavy chronic cannabis users. It is currently unknown whether neurocognitive impairment occurs with low blood THC concentrations, and whether return to normal performance, as documented previously following extended cannabis abstinence, is accompanied by the removal of residual THC in brain. These findings also may impact on the implementation of per se limits in driving under the influence of drugs legislation.

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  • Authors+Show Affiliations

    ,

    Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.

    , , , , , ,

    Source

    Addiction (Abingdon, England) 104:12 2009 Dec pg 2041-8

    MeSH

    Adult
    Biomarkers
    Dronabinol
    Female
    Gas Chromatography-Mass Spectrometry
    Humans
    Male
    Marijuana Abuse
    Middle Aged
    Psychotropic Drugs
    Substance Abuse Detection
    Young Adult

    Pub Type(s)

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

    Language

    eng

    PubMed ID

    19804462

    Citation

    TY - JOUR T1 - Do Delta9-tetrahydrocannabinol concentrations indicate recent use in chronic cannabis users? AU - Karschner,Erin L, AU - Schwilke,Eugene W, AU - Lowe,Ross H, AU - Darwin,W David, AU - Pope,Harrison G, AU - Herning,Ronald, AU - Cadet,Jean L, AU - Huestis,Marilyn A, Y1 - 2009/10/05/ PY - 2009/10/7/entrez PY - 2009/10/7/pubmed PY - 2010/3/18/medline SP - 2041 EP - 8 JF - Addiction (Abingdon, England) JO - Addiction VL - 104 IS - 12 N2 - AIMS: To quantify blood Delta(9)-tetrahydrocannabinol (THC) concentrations in chronic cannabis users over 7 days of continuous monitored abstinence. PARTICIPANTS: Twenty-five frequent, long-term cannabis users resided on a secure clinical research unit at the US National Institute on Drug Abuse under continuous medical surveillance to prevent cannabis self-administration. MEASUREMENTS: Whole blood cannabinoid concentrations were determined by two-dimensional gas chromatography-mass spectrometry. FINDINGS: Nine chronic users (36%) had no measurable THC during 7 days of cannabis abstinence; 16 had at least one positive THC > or =0.25 ng/ml, but not necessarily on the first day. On day 7, 6 full days after entering the unit, six participants still displayed detectable THC concentrations [mean +/- standard deviation (SD), 0.3 +/- 0.7 ng/ml] and all 25 had measurable carboxy-metabolite (6.2 +/- 8.8 ng/ml). The highest observed THC concentrations on admission (day 1) and day 7 were 7.0 and 3.0 ng/ml, respectively. Interestingly, five participants, all female, had THC-positive whole blood specimens over all 7 days. Body mass index did not correlate with time until the last THC-positive specimen (n = 16; r = -0.2; P = 0.445). CONCLUSIONS: Substantial whole blood THC concentrations persist multiple days after drug discontinuation in heavy chronic cannabis users. It is currently unknown whether neurocognitive impairment occurs with low blood THC concentrations, and whether return to normal performance, as documented previously following extended cannabis abstinence, is accompanied by the removal of residual THC in brain. These findings also may impact on the implementation of per se limits in driving under the influence of drugs legislation. SN - 1360-0443 UR - https://www.unboundmedicine.com/medline/citation/19804462/full_citation/Do_Delta_9__tetrahydrocannabinol_concentrations_indicate_recent_use_in_chronic_cannabis_users L2 - https://doi.org/10.1111/j.1360-0443.2009.02705.x ER -