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Message: <blockquote data-quote="420 News" data-source="post: 1374993" data-attributes="member: 81103">Extended urinary Delta9-tetrahydrocannabinol excretion in chronic cannabis users precludes use as a biomarker of new drug exposureAuthor(s)    Lowe RH, Abraham TT, Darwin WD, Herning R, Cadet JL, Huestis MA Institution    Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Suite 05A721, Baltimore, MD 21224, USA.Source    Drug Alcohol Depend 2009 Nov 1; 105(1-2):24-32.MeSH    AdultBiological MarkersChronic DiseaseEthnic GroupsFemaleGas Chromatography-Mass SpectrometryHumansMaleMarijuana AbuseSubstance Abuse DetectionSubstance-Related DisordersTetrahydrocannabinolYoung AdultAbstract    BACKGROUND: Generally, urinary 11-nor-9-carboxy-Delta9-tetrahydrocannabinol (THCCOOH) after alkaline hydrolysis is monitored to detect cannabis exposure, although last use may have been weeks prior in chronic cannabis users. Delta9-Tetrahydrocannabinol (THC) and 11-hydroxy-THC (11-OH-THC) concentrations in urine following Escherichia coli beta-glucuronidase hydrolysis were proposed as biomarkers of recent (within 8h) cannabis use.OBJECTIVE: To test the validity of THC and 11-OH-THC in urine as indicators of recent cannabis use.METHODS: Monitor urinary cannabinoid excretion in 33 chronic cannabis smokers who resided on a secure research unit under 24h continuous medical surveillance. All urine specimens were collected individually ad libidum for up to 30 days, were hydrolyzed with a tandem E. coli beta-glucuronidase/base procedure, and analyzed for THC, 11-OH-THC and THCCOOH by one- and two-dimensional-cryotrap gas chromatography mass spectrometry (2D-GCMS) with limits of quantification of 2.5 ng/mL.RESULTS: Extended excretion of THC and 11-OH-THC in chronic cannabis users' urine was observed during monitored abstinence; 14 of 33 participants had measurable THC in specimens collected at least 24h after abstinence initiation. Seven subjects had measurable THC in urine for 3, 3, 4, 7, 7, 12, and 24 days after cannabis cessation. 11-OH-THC and THCCOOH were detectable in urine specimens from one heavy, chronic cannabis user for at least 24 days.CONCLUSION: For the first time, extended urinary excretion of THC and 11-OH-THC is documented for at least 24 days, negating their effectiveness as biomarkers of recent cannabis exposure, and substantiating long terminal elimination times for urinary cannabinoids following chronic cannabis smoking.Language    engPub Type(s)    Journal ArticleResearch Support, N.I.H., IntramuralPubMed ID    19631478Source: <a href="http://www.unboundmedicine.com/medline/ebm/record/19631478/full_citation/Extended_urinary_Delta9_tetrahydrocannabinol_excretion_in_chronic_cannabis_users_precludes_use_as_a_biomarker_of_new_drug_exposure_" target="_blank">Extended urinary Delta9-tetrahydrocannabinol excretion in chronic cannabis users precludes use as a biomarker of new drug exposure</a></blockquote>

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