Huestis M A, Mitchell J M, Cone E J
Chemistry and Drug Metabolism Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
J Anal Toxicol. 1995 Oct;19(6):443-9. doi: 10.1093/jat/19.6.443.
Reports of prolonged drug excretion have provided the basis for the common assumption that cannabinoid metabolites may he detected in urine for a week or longer. The accuracy, sensitivity, and specificity of immunoassays for the detection of cannabinoids and metabolites are unique for a specific assay and may change overtime. it is important that individuals who select assays and those who interpret test results be aware of qualitative and quantitative changes that occur. In the present study, detection times of cannabinoids in urine were determined using cannabinoid immunoassays with 20-, 50-, and 100-ng/mL cutoffs and using gas chromatography-mass spectrometry (GC-MS). Six subjects each smoked a single marijuana cigarette (placebo, 1.75, or 3.55% delta9-tetrahydrocannabinol [THC]) each week while residing on the clinical ward of the Addiction Research Center. Each urine specimen was analyzed under blind conditions by immunoassay according to the manufacturer's instructions. The following cannabinoid reagents were evaluated: EMIT d.a.u. 100, EMIT d.a.u. 50, EMIT d.a.u. 20, EMIT II 100, EMIT II 50, Abuscreen OnLine, and Abuscreen RIA, DRI, and ADx. All urine specimens were also analyzed for 11-nor-9-carboxy-delta9-THC by GC-MS using a 15-ng/mL cutoff. Urinary cannabinoid detection times varied substantially across assays, subjects, doses, and cutoff concentrations. Detection times were shorter than previously assumed. Mean detection times increased from a maximum of 0.5 days after the low dose to 1.5 days after the high dose using the 100-ng/mL cutoff. Mean detection times were less than 1 day following the low dose and less than 2 days following high-dose exposure using the 50-ng/mL cutoff. Mean detection times ranged from 1 to 5 days after the low dose and from 3 to 6 days after the high dose using the 20-ng/mL cutoff immunoassay. GC-MS detection times were approximately twice as long as mean detection times using an immunoassay with a cutoff of 50 ng/mL. Differences in sensitivity and specificity between the available immunoassay products affected the efficiency of detection of marijuana use. These results indicate that recent reductions in cannabinoid cutoffs by military and federally mandated programs will increase detection times and improve sensitivity, as expected. However, monitoring acute marijuana usage with a commercial cannabinoid immunoassay that has a 50-ng/mL cutoff concentration provides only a narrow window of detection of 1-2 days.
关于药物排泄时间延长的报告为一种普遍假设提供了依据，即大麻素代谢物可能在尿液中被检测到一周或更长时间。免疫分析法检测大麻素和代谢物的准确性、灵敏度和特异性因特定检测方法而异，且可能随时间变化。选择检测方法的人员和解读检测结果的人员必须了解所发生的定性和定量变化，这一点很重要。在本研究中，使用大麻素免疫分析法，其临界值分别为20、50和100纳克/毫升，并采用气相色谱 - 质谱联用仪（GC-MS）来确定尿液中大麻素的检测时间。六名受试者在成瘾研究中心临床病房住院期间，每周每人吸食一支大麻香烟（安慰剂、含1.75%或3.55%的delta9 - 四氢大麻酚[THC]）。每个尿液样本按照制造商的说明在盲态条件下通过免疫分析法进行分析。评估了以下大麻素检测试剂：EMIT d.a.u. 100、EMIT d.a.u. 50、EMIT d.a.u. 20、EMIT II 100、EMIT II 50、Abuscreen OnLine、Abuscreen RIA、DRI和ADx。所有尿液样本还通过GC-MS分析11 - 去甲 - 9 - 羧基 - delta9 - THC，临界值为15纳克/毫升。尿液中大麻素的检测时间在不同的检测方法、受试者、剂量和临界浓度之间有很大差异。检测时间比之前假设的要短。使用100纳克/毫升的临界值时，平均检测时间从低剂量后的最长0.5天增加到高剂量后的1.5天。使用50纳克/毫升的临界值时，低剂量后平均检测时间不到1天，高剂量暴露后不到2天。使用20纳克/毫升临界值的免疫分析法时，低剂量后平均检测时间为1至5天，高剂量后为3至6天。GC-MS的检测时间约为使用临界值50纳克/毫升的免疫分析法平均检测时间的两倍。现有免疫分析产品在灵敏度和特异性上的差异影响了对大麻使用检测的效率。这些结果表明，正如预期的那样，军事和联邦强制项目近期降低大麻素临界值将增加检测时间并提高灵敏度。然而，使用临界浓度为50纳克/毫升的商用大麻素免疫分析法监测急性大麻使用情况，其检测窗口期仅为1至2天。
