Serum Cannabinoid Fingerprints Did Not Reliably Separate Medical and Street Cannabis
A broad serum cannabinoid panel did not reliably distinguish THC-rich medical cannabis from street cannabis in a pilot study. More analytes supplied useful patterns, but they did not create a universal test for prescription-source attribution.
Different products were represented
The study recruited 23 patients receiving cannabis-based medicines or medical cannabis and collected repeated serum samples. Researchers measured eighteen cannabinoids and compared patterns with 55 previously analyzed forensic serum samples from street-cannabis users.
The medicinal products included dronabinol, a THC/CBD oromucosal spray and several cannabis varieties. Timing, doses and additional cannabis use were based on participant reports. Repeated specimens did not represent additional independent patients.
Some product groups separated; plant cannabis overlapped
Dronabinol and spray samples showed potentially informative metabolite and minor-cannabinoid patterns relative to cannabis samples. However, THC-rich medical cannabis and street-cannabis samples generally occupied overlapping regions in the principal-component analysis. One CBD-rich medical-cannabis specimen separated from much of that group.
That single specimen does not establish that all prescribed cannabis strains are distinguishable. Nor does a visible separation in an exploratory plot provide sensitivity, specificity or a validated probability of source for an unfamiliar individual specimen.
Reported history was not an independent source standard
The investigators acknowledged small subgroups, self-reported timing and intake, possible individual metabolic differences and repeated sampling. Minor-cannabinoid detection windows were incompletely understood. Some statistical differences also depended on whether multiple-comparison adjustment was applied.
The findings can help frame follow-up questions about formulation and exposure history. They cannot establish that a person lied about a prescription, identify legal supply status from serum alone or resolve which product caused a functional effect. Product records, actual formulation and timing remain relevant evidence.
A serum pattern is also a different question from impairment. An apparent match to a medicine does not prove normal driving, and overlap with a street-cannabis group does not independently prove impaired driving or unprescribed consumption.
Related: interpreting THC concentrations separately from impairment.
Primary research
Identification of Potential Distinguishing Markers for the Use of Cannabis-Based Medicines or Street Cannabis in Serum Samples. DOI: 10.3390/metabo11050316.
