CBD did not change how the body absorbs or processes THC at therapeutic doses
In 9 cannabis smokers, Sativex and equivalent oral THC doses produced nearly identical THC blood levels, indicating CBD's effects on THC are not due to changing THC absorption or metabolism.
Quick Facts
What This Study Found
Researchers measured plasma levels of cannabinoids after administering Sativex (THC+CBD) and pure oral THC to determine whether CBD alters THC pharmacokinetics.
Nine cannabis smokers received five treatments in randomized, double-blind sessions: placebo, low and high oral THC, and low and high Sativex doses. Blood was drawn at multiple time points over 10.5 hours.
There were no significant differences in peak plasma THC concentration, time to peak, or total THC exposure between equivalent oral THC and Sativex doses. Relative bioavailability calculations showed oral THC at 5 and 15 mg was 92.6% and 98.8% of Sativex, respectively, nearly identical.
These data demonstrated that whatever effects CBD has on THC are not due to pharmacokinetic interactions (changing absorption or metabolism) at therapeutic doses.
Key Numbers
9 completers. THC bioavailability: 92.6% (5 mg) and 98.8% (15 mg) of equivalent Sativex doses. No significant differences in Cmax, Tmax, or AUC between oral THC and Sativex.
How They Did This
Randomized, double-blind, placebo-controlled, five-session crossover study. 9 cannabis smokers. CBD, THC, 11-OH-THC, and THC-COOH quantified in plasma by 2D GC-MS. Lower limits of quantification at 0.25 mcg/L or below.
Why This Research Matters
Ruling out pharmacokinetic interaction meant that any CBD modulation of THC effects would have to be pharmacodynamic (at the receptor level), which informed the design of future combination products.
The Bigger Picture
This pharmacokinetic study was important for understanding how CBD and THC interact in pharmaceutical products, establishing that CBD did not act as a metabolic modifier of THC at the doses tested.
What This Study Doesn't Tell Us
Very small sample (9 participants). Only therapeutic doses tested. Cannabis smokers may metabolize cannabinoids differently than naive users. Single-dose pharmacokinetics may differ from steady-state with chronic dosing.
Questions This Raises
- ?Does CBD affect THC pharmacokinetics at higher doses or with chronic use?
- ?If CBD's interaction is pharmacodynamic, what receptors mediate the modulation?
Trust & Context
- Key Stat:
- THC bioavailability was 93-99% equivalent between Sativex and pure oral THC
- Evidence Grade:
- Well-designed pharmacokinetic study with rigorous analytical methods but very small sample.
- Study Age:
- Published in 2011. CBD-THC pharmacokinetic interaction research has continued.
- Original Title:
- Plasma cannabinoid pharmacokinetics following controlled oral delta9-tetrahydrocannabinol and oromucosal cannabis extract administration.
- Published In:
- Clinical chemistry, 57(1), 66-75 (2011)
- Authors:
- Karschner, Erin L(4), Darwin, W David, Goodwin, Robert S(6), Wright, Stephen, Huestis, Marilyn A
- Database ID:
- RTHC-00494
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Does CBD change how the body processes THC?
At the doses tested in this study, no. THC blood levels were nearly identical whether given alone or with CBD in Sativex, indicating CBD does not affect THC absorption or metabolism at therapeutic doses.
Then how might CBD modify THC effects?
If CBD modifies THC effects (which was not clearly shown at these doses), it would have to be through pharmacodynamic interactions, meaning at the receptor level in the brain, rather than by changing THC blood levels.
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Cite This Study
https://rethinkthc.com/research/RTHC-00494APA
Karschner, Erin L; Darwin, W David; Goodwin, Robert S; Wright, Stephen; Huestis, Marilyn A. (2011). Plasma cannabinoid pharmacokinetics following controlled oral delta9-tetrahydrocannabinol and oromucosal cannabis extract administration.. Clinical chemistry, 57(1), 66-75. https://doi.org/10.1373/clinchem.2010.152439
MLA
Karschner, Erin L, et al. "Plasma cannabinoid pharmacokinetics following controlled oral delta9-tetrahydrocannabinol and oromucosal cannabis extract administration.." Clinical chemistry, 2011. https://doi.org/10.1373/clinchem.2010.152439
RethinkTHC
RethinkTHC Research Database. "Plasma cannabinoid pharmacokinetics following controlled ora..." RTHC-00494. Retrieved from https://rethinkthc.com/research/karschner-2011-plasma-cannabinoid-pharmacokinetics-following
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.