Assessing cannabis consumption frequency: Is the combined use of free and glucuronidated THCCOOH blood levels of diagnostic utility?

Cannabis Use and Biomarkers of Inflammation, Immune Activation, and Microbial Translocation in Persons with HIV

Background: The relationship between cannabis and inflammation among persons with HIV (PWH) remains unclear. We examined whether the cannabis metabolite 11-nor-9-carboxy THC (THC-COOH) is associated with lower levels of plasma biomarkers of inflammation, immune activation, and microbial translocation in PWH. We hypothesized that cannabis use would be associated with lower levels of plasma inflammatory biomarkers than noncannabis use. Methods: We quantified THC-COOH in plasma, with THC-COOH levels between 5.1-69.9 μg/L and ≥70 μg/L being classified as moderate and heavy cannabis use, respectively, with noncannabis use defined as undetected THC-COOH. We measured a panel of plasma biomarkers of inflammation (interleukin [IL]-1-β, tumor necrosis factor-alpha, IL-18, IL-6, and C-reactive protein), immune activation (CD14 and CD163), and microbial translocation (iFABP2 and lipopolysaccharide binding protein [LBP]), with all biomarkers collected on the same day. We used a cross-sectional design and linear regression models to test whether cannabis use is associated with lower biomarker levels. Results: Participants were (N=107) sexual minority men with HIV (median age=32 years, IQR=28, 38), of whom 65% were virally suppressed; 36%, 44%, and 20% were classified as nonuse, moderate, and heavy cannabis, respectively. In linear regression models adjusted for viral suppression, stimulant use, and CD4 counts, heavy cannabis use was significantly associated with lower levels of log10 LBP (β=-0.14, 95% confidence interval: -0.24 to -0.04; false discovery rate=0.0029; partial eta squared=0.07) than noncannabis users. No precise associations were observed for other biomarkers (all p>0.05). Conclusions: Our findings suggest that cannabis use may be associated with lower plasma LBP. Further work is needed to clarify the relationship between cannabis use and biomarkers of microbial translocation in PWH.

Cytosolic Enzymes Generate Cannabinoid Metabolites 7-Carboxycannabidiol and 11-Nor-9-carboxytetrahydrocannabinol

The cannabinoids cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) undergo extensive oxidative metabolism in the liver. Although cytochromes P450 form the primary, pharmacologically active, hydroxylated metabolites of CBD and THC, less is known about the enzymes that generate the major in vivo circulating metabolites of CBD and THC, 7-carboxy-CBD and 11-carboxy-THC, respectively. The purpose of this study was to elucidate the enzymes involved in forming these metabolites. Cofactor dependence experiments with human liver subcellular fractions revealed that 7-carboxy-CBD and 11-carboxy-THC formation is largely dependent on cytosolic NAD+-dependent enzymes, with lesser contributions from NADPH-dependent microsomal enzymes. Experiments with chemical inhibitors provided evidence that 7-carboxy-CBD formation is mainly dependent on aldehyde dehydrogenases and 11-carboxy-THC formation is mediated also in part by aldehyde oxidase. This study is the first to demonstrate the involvement of cytosolic drug-metabolizing enzymes in generating major in vivo metabolites of CBD and THC and addresses a knowledge gap in cannabinoid metabolism.

Objective Identification of Cannabis Use Levels in Clinical Populations Is Critical for Detecting Pharmacological Outcomes

Introduction: Cannabis is widely used for recreational and medical purposes, but its therapeutic efficacy remains unresolved for many applications as data from retrospective studies show dramatic discrepancy. We hypothesized that false self-reporting of cannabis use and lack of differentiation of heavy users from light or occasional users contribute to the conflicting outcomes. Objective: The goal of this study was to develop an objective biomarker of cannabis use and test how application of such biomarker impacts clinical study outcomes and dose-response measures. Methods and Analysis: Population pharmacokinetic (PK) models of (-)-trans-Δ9-tetrahydrocannabinol (THC) and its metabolites 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (11-COOH-THC) were developed based on published studies reporting cannabinoid disposition in individual subjects following intravenous administration or smoking of cannabis. Plasma 11-COOH-THC concentration distributions in different cannabis user groups smoking cannabis were generated via Monte Carlo simulations, and plasma concentration cutoff values of 11-COOH-THC were developed to differentiate light and heavy daily cannabis users in clinical studies. The developed cutoff value was then applied to a retrospective study that assessed the impact of cannabis use on T cell activation in subjects with HIV who self-reported as either nonuser or daily user of cannabis. Results: The developed population PK models established plasma 11-COOH-THC concentration of 73.1 μg/L as a cutoff value to identify heavy daily users, with a positive predictive value of 80% in a mixed population of equal proportions of once daily and three times a day users. The stratification allowed detection of changes in T cell activation in heavy users which was not detected based on self-reporting or detectability of plasma cannabinoids. A proof-of-concept power analysis demonstrated that implementation of such cutoff value greatly increases study power and sensitivity to detect pharmacological effects of cannabis use. Conclusions: This study shows that the use of plasma 11-COOH-THC concentration cutoff value as an objective measure to classify cannabis use in target populations is critical for study sensitivity and specificity and provides much needed clarity for addressing dose-response relationships and therapeutic effects of cannabis.

Quantitative determination of five cannabinoids in blood and urine by gas chromatography tandem mass spectrometry applying automated on-line solid phase extraction

Cannabis is the most frequently consumed illegal substance worldwide. More recently, an increasing number of legal cannabis products low in psychoactive Δ⁹‐tetrahydrocannabinol (THC) but high in non‐intoxicating cannabidiol (CBD) are being more widely consumed. While the detection and quantification of THC and its metabolites in biological matrices is an important forensic‐toxicological task, additional detection of CBD is also important, for example, when examining the plausibility of consumer's statements. This report describes the method validation for the quantitative determination of THC and its two major metabolites, 11‐hydroxy‐THC (OH‐THC) and 11‐nor‐9‐carboxy‐THC (THC‐COOH), as well as CBD and cannabinol (CBN) in whole blood and urine. The method employs automated on‐line solid phase extraction coupled to gas chromatography tandem mass spectrometry (GC–MS/MS). The method was fully validated according to guidelines of the Swiss Society of Legal Medicine (SGRM) and the Society of Toxicological and Forensic Chemistry (GTFCh). The method fulfilled the validation criteria regarding analytical limits, accuracy and precision, extraction efficacy, and sample stability. The limits of detection (LODs) in whole blood and urine were 0.15 ng/mL for THC, OH‐THC and CBD, 0.1 ng/mL for CBN, and 1.0 ng/mL for THC‐COOH. The limits of quantification (LOQ) in whole blood and urine were 0.3 ng/mL for THC, OH‐THC and CBD, 0.2 ng/mL for CBN, and 3.0 ng/mL for THC‐COOH. The fully validated and automated method allows sensitive and robust measurement of cannabinoids in whole blood and urine. Detection of CBD provides additional information regarding consumed products.

Identifying and Quantifying Cannabinoids in Biological Matrices in the Medical and Legal Cannabis Era

Background

Cannabinoid analyses generally included, until recently, the primary psychoactive cannabis compound, Δ9-tetrahydrocannabinol (THC), and/or its inactive metabolite, 11-nor-9-carboxy-THC, in blood, plasma, and urine. Technological advances revolutionized the analyses of major and minor phytocannabinoids in diverse biological fluids and tissues. An extensive literature search was conducted in PubMed for articles on cannabinoid analyses from 2000 through 2019. References in acquired manuscripts were also searched for additional articles.

Content

This article summarizes analytical methodologies for identification and quantification of multiple phytocannabinoids (including THC, cannabidiol, cannabigerol, and cannabichromene) and their precursors and/or metabolites in blood, plasma, serum, urine, oral fluid, hair, breath, sweat, dried blood spots, postmortem matrices, breast milk, meconium, and umbilical cord since the year 2000. Tables of nearly 200 studies outline parameters including analytes, specimen volume, instrumentation, and limits of quantification. Important diagnostic and interpretative challenges of cannabinoid analyses are also described. Medicalization and legalization of cannabis and the 2018 Agricultural Improvement Act increased demand for cannabinoid analyses for therapeutic drug monitoring, emergency toxicology, workplace and pain-management drug testing programs, and clinical and forensic toxicology applications. This demand is expected to intensify in the near future, with advances in instrumentation performance, increasing LC-MS/MS availability in clinical and forensic toxicology laboratories, and the ever-expanding knowledge of the potential therapeutic use and toxicity of phytocannabinoids.

Summary

Cannabinoid analyses and data interpretation are complex; however, major and minor phytocannabinoid detection windows and expected concentration ranges in diverse biological matrices improve the interpretation of cannabinoid test results.