Detectability of various cannabinoids in plasma samples of cannabis users: Indicators of recent cannabis use?

Abstract

Despite many studies on cannabinoid pharmacokinetics, the proposals of marker cannabinoids for recent cannabis use, and the introduction of mathematical models estimating the time frame between consumption and blood sampling, it is still challenging for forensic toxicologists to estimate the last time of cannabis exposure. To assess the informative value of determining (minor) cannabinoids in plasma of cannabis users, detection rates of 14 cannabinoids next to Δ9‐THC and THC‐COOH (11‐OH‐THC, CBC, CBD, CBN, CBDV, THCV, CBG, CBL, Δ8‐THC, THCA, CBDA, CBGA, THCV‐COOH, CBN‐COOH) were determined. Three hundred fifty‐five plasma samples, previously tested positive for cannabinoids (Δ9‐THC: approximately 0.4 ng/mL – 125 ng/mL (range), mean: 10.1 ng/mL; THC‐COOH: approximately 3.8 ng/mL – 457 ng/mL (range), mean: 71.6 ng/mL) were analyzed by means of liquid chromatography−tandem mass spectrometry (LC–MS/MS). All analyzed cannabinoids could be detected in plasma samples with varying incidence. 11‐OH‐THC, THCA, CBC, CBN, and CBD were the most frequent detectable cannabinoids (next to Δ9‐THC and THC‐COOH). The dependency of cannabinoid detectability on the plasma Δ9‐THC concentration and on the probable time of consumption (estimated by a model of Huestis and coworkers) was examined. Detection incidences (eg, 11‐OH‐THC, CBC) often increased with increasing Δ9‐THC concentration but not for all cannabinoids (eg, CBD, THCA). The presented data for minor cannabinoid findings in plasma can be helpful for a comprehensive interpretation of cannabinoid findings in plasma samples of cannabis users.

Detectability of cannabinoids in the serum samples of cannabis users: Indicators of recent cannabis use? A follow‐up study

“…In a previous study, 16 we evaluated the detection rates of (minor) cannabinoids/cannabinoid metabolites among plasma samples previously tested positive for delta‐9‐THC or its metabolites. The dependency of cannabinoid concentration or detectability on the plasma delta‐9‐THC concentration or on the probable time of consumption (estimated by a mathematical model of Huestis et al 5 ) was examined.…”

“…20 The degree of conversion of precursor acids (which are predominantly present in the plant material) to the corresponding cannabinoids was indicated to depend on the reaction temperature (e.g., during baking hash cookies or smoking a marijuana cigarette). 23 Accordingly, depending on the reaction temperature, different pro- In a previous study, 16 we evaluated the detection rates of (minor) cannabinoids/cannabinoid metabolites among plasma samples previously tested positive for delta-9-THC or its metabolites. The dependency of cannabinoid concentration or detectability on the plasma delta-9-THC concentration or on the probable time of consumption (estimated by a mathematical model of Huestis et al 5 ) was examined.…”

“…34 In the case of chronic users, the increased inaccuracy results particularly from residual delta-9-THC (and THCCOOH) concentrations 35 that may be detectable over long periods of time despite abstinence. 11,12 Thus, it was already mentioned in our previous study 16 that in order to further evaluate the marker suitability of minor cannabinoids, it is necessary to examine samples of patients with known (or self-reported) consumption history.…”

“…Based on the assumption that a high plasma delta-9-THC concentration is indicative of a short period between consumption and blood sampling, several minor cannabinoids were preferentially detected in samples taken from subjects with short intervals between use and sampling (or correspondingly higher delta-9-THC concentrations). 16 In the present study, we analyzed 117 serum samples from individuals (psychiatric patients) with self-reported cannabis consumption via liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (LC-MS/MS) to assess the detectability of cannabinoids/cannabinoid metabolites that might be useful for evaluating recent cannabis exposure. The analysis results were evaluated in consideration of the last time of consumption and consumption frequencies reported by the patients.…”

“…In a previous investigation, we determined the detection rates of minor cannabinoids/cannabinoid metabolites in plasma samples with varying delta‐9‐THC concentrations. Based on the assumption that a high plasma delta‐9‐THC concentration is indicative of a short period between consumption and blood sampling, several minor cannabinoids were preferentially detected in samples taken from subjects with short intervals between use and sampling (or correspondingly higher delta‐9‐THC concentrations) 16 …”