Topic: Tox / TDM / Endocrine
Podium Presentation in Room 1 on Wednesday at 11:00 (Chair: Jen Colby / Chris Koch)
Authors: Gregory Janis, Melissa Goggin
Introduction: Detecting marijuana use is a component of millions of urine drug screens. These assays target a single carboxylated metabolite of the primary psychoactive component in marijuana, Δ9-tetrahydrocannabinol (THC). THC is just one of many cannabinoids found in cannabis. Recently the non-intoxicating cannabinoid, cannabidiol (CBD), has gained popular acceptance as a natural remedy for a variety of medical conditions. A resulting meteoric rise in the demand for CBD has been met by an exponential proliferation of commercially available CBD products. However, unlike state administered medical and recreational marijuana, commercially available CBD products are sold without regulations on quality or purity. Consequentially, many CBD products contain low level THC contamination. Long-term or high dose use of THC contaminated CBD products can result in significant THC exposures capable of producing a positive marijuana drug test. These results are not true false positives as marijuana biomarkers are present, but misleadingly identify a donor as a marijuana user.
Objective: To develop a process discriminating marijuana use from the use of CBD contaminated with THC.
Methods: Following the in-house synthesis of a primary metabolite of CBD, 7-carboxy-CBD (COOH-CBD) a LC-MS/MS assay was developed to measure the primary urinary metabolites THC, COOH-THC, CBD, and COOH-CBD all released from their respective glucuronide conjugates. The assay was exercised on a large pool of pain management patients claiming CBD use. These donors may have exclusively consumed CBD, used CBD in combination with marijuana, or claimed CBD use as a method to explain away a positive marijuana test.
Results: Clear clusters in the data were evident. 43% of samples contained CBD metabolites at greater than a ten-fold excess to THC metabolites while 26% of these samples contained measurable COOH-THC. 17% of samples contained THC metabolites in excess of CBD metabolites. 9% of samples contained CBD metabolites in excess of THC metabolites, but at levels less than a ten-fold excess.
Based upon the results, metabolic cut-points were assigned. A ten-fold excess of CBD metabolites relative to THC metabolites classified donors as CBD users. An excess of THC metabolites classified donors as marijuana users. Ratios between the two were classified as indeterminate from users of both CBD and THC or users of heavily contaminated CBD. To validate these cut-points, a set of urine samples were procured from donors personally known to use commercial CBD ad libitum, while abstaining from THC. Results from the trusted user group substantiated the use of the test and resulting metabolic ratios to successfully differentiate CBD use from marijuana use despite 75% of these known samples containing measurable levels of COOH-THC.
Conclusion: An assay was developed and deployed identifying when a positive urine THC test resulted from consumption of contaminated CBD products.
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