The THC/CBD interaction study planned twelve volunteers for each medication group without a formal sample-size power calculation. That matters when interpreting an unobserved difference or a broad safety claim.
The design was a small Phase I experiment
Thirty-six healthy men entered three groups, each assigned one interacting medication. Within a group, the crossover compared THC/CBD spray alone with the combination. The authors explicitly reported no formal sample-size power calculation, and some analyses used fewer completers.
The groups were analyzed separately. Thirty-six enrolled participants should not be described as thirty-six paired observations supporting each medication-specific interaction result.
A null finding has limited reach
Omeprazole did not significantly alter the measured pharmacokinetic profile under this protocol. That does not demonstrate the absence of every smaller effect or establish equivalence for all patients and doses. Precision depends on actual variability and the available paired sample, not enrollment alone.
Safety requires the same restraint
A small selected healthy-volunteer study can describe observed tolerability and exposure changes. It cannot exclude rare adverse events or represent people with major illness and multiple medications. The appropriate use is to retain the exact comparison, uncertainty and product tested rather than turn a limited null result into a universal interaction-free label.
Related reading: interpreting proposed CBD mechanisms.
Research cited
Stott and colleagues (2013). A Phase I, open-label, randomized, crossover study in three parallel groups to evaluate the effect of Rifampicin, Ketoconazole, and Omeprazole on the pharmacokinetics of THC/CBD oromucosal spray in healthy volunteers. DOI: 10.1186/2193-1801-2-236.
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