A wide variety of preparations are available for treatment with cannabis-based medicines, including Dronabinol capsules and oils, the oromucosal spray Sativex, full-spectrum cannabis extracts and flowers. In particular, the number of medicinal cannabis flowers available in Germany has risen considerably in recent years, from 28 cultivars in 2019 [1] to over 200 cultivars today [2]. At the same time, the number of prescriptions for cannabis-based medicines has increased substantially, from 185,370 in 2018 to 393,187 in 2022 [3]. However, these statistics only include patients with statutory health insurance and not self-paying or privately insured patients, so the actual number of prescriptions, especially for cannabis flowers, may be significantly higher.
If there are no signs of impairment, participation in road traffic is permitted after use of medicinal cannabis according to the German Road Traffic Act. This exemption justifies the need to distinguish between the use of cannabis-based medicines and recreational cannabis use. Legalisation may further increase the frequency and complexity of such questions. However, such a distinction is challenging from an analytical point of view, as medicinal and recreational cannabis varieties originate from common illegally bred cultivars. An analytical examination of a blood sample must therefore go far beyond the usual detection of THC and its metabolites. Various approaches to comprehensive analysis have been proposed in the literature, including the examination of minor cannabinoids using LC-MS/MS methods [4]. Untargeted high-resolution mass spectrometry was proposed (‘Cannabinomics’) [5], although its applicability to blood samples is still unclear. An additional GC-MS based analysis of terpenes, known as odorants and possible entourage compounds, in combination with cannabinoids may offer a new way to achieve a refined distinction between different cultivars.
At present, it is not (yet) scientifically possible to clearly differentiate between medicinal and recreational use of cannabis based on a blood sample. In individual cases, e.g. after the consumption of CBD-dominant strains or dronabinol capsules, plausibility tests are possible. However, further research is needed, especially regarding the differentiation of cannabis flowers.
Literature:
[1] Müller-Vahl K, Grotenhermen F, Cannabis und Cannabinoide in der Medizin, 2019, MWV.
[2] Arbeitsgemeinschaft Cannabis als Medizin e.V., 2023, https://www.arbeitsgemeinschaftcannabis- medizin.de/wp-content/uploads/2023/09/Cannabissorten_Inhaltsstoffe-1.pdf, (accessed 11/01/2024).
[3] GKV-Spitzenverband, Sonderbeilage zur GKV-Arzneimittel-Schnellinformation für Deutschland, 2019 - 2023, https://www.gkv-gamsi.de, (accessed 11/01/2024).
[4] Scheunemann A, Elsner K, Germerott T, et al., Metabolites. 2021, 11, 5.
[5] Monti M, Frei P, Weber S, et al., Anal Bioanal Chem. 2022, 414, 13.
