Saliva Patterns After THC Capsules and Oromucosal Spray Did Not Support the Same Compliance Inference
Observed THC capsule dosing and THC/CBD mouth-spray dosing produced very different saliva patterns. A test used to monitor treatment must be matched to how the medicine enters the body.
Five conditions in fourteen people
Fourteen cannabis users completed randomized sessions with low- and higher-dose swallowed THC, low- and higher-dose THC/CBD spray, and placebo. Oral fluid was collected before dosing and for 10.5 hours afterward.
Capsules supplied 5 or 15 mg THC. Spray doses supplied 5.4 mg THC plus 5 mg CBD, or 16.2 mg THC plus 15 mg CBD. The experiment studied disposition, not an impairment diagnosis.
Local deposition changed the signal
After swallowed THC, parent THC generally declined from baseline and did not significantly differ from placebo after adjustment. Residual exposure before the session was important.
Spray administration substantially increased oral-fluid THC, CBD and CBN. The medicine directly contacted the mouth, creating a local cannabinoid source. This signal cannot be treated as though it came entirely from blood.
Adherence and additional smoking differ
The authors considered the high CBD-to-THC pattern potentially useful for documenting spray use. Absent parent THC did not reliably establish that a swallowed capsule had not been taken.
The spray’s own contamination complicated identifying additional smoked cannabis during treatment. A proposed ratio supporting recent exposure was not an exclusionary rule. One result cannot automatically establish adherence, detect every additional exposure and measure impairment.
Limits remain important
Baseline positivity, varied cannabis histories, a small sample and the 10.5-hour observation period constrain interpretation. Analyte-specific quantification limits also affected detection.
The paper contains an inconsistent final reference to the ratio characterizing spray use; its results and discussion identify CBD/THC as the relevant high ratio. Interpretation should follow those data rather than repeat isolated contradictory wording.
For the separate forensic question, see our discussion of cannabinoid concentrations and evidence of impairment.
Primary research
Can oral fluid cannabinoid testing monitor medication compliance and/or cannabis smoking during oral THC and oromucosal Sativex administration?. Drug and alcohol dependence (2012). DOI: 10.1016/j.drugalcdep.2012.10.011.
