CBD and clobazam work better together through both drug interaction and direct brain effects
CBD enhanced clobazam's anti-seizure effects in a Dravet syndrome mouse model through two distinct mechanisms: increasing clobazam blood levels (pharmacokinetic) and directly enhancing GABA receptor activity together (pharmacodynamic).
Quick Facts
What This Study Found
CBD potently inhibited liver enzymes (CYP3A4, CYP2C19) that metabolize clobazam and its metabolite, increasing plasma clobazam levels. However, a sub-anticonvulsant dose of CBD did not improve seizure outcomes despite raising clobazam levels, while an anticonvulsant dose did. This proves the interaction is not purely pharmacokinetic. CBD and clobazam together also enhanced inhibitory GABA receptor activation, revealing a novel pharmacodynamic mechanism.
Key Numbers
CBD potently inhibited CYP3A4-mediated clobazam metabolism and CYP2C19-mediated N-desmethylclobazam metabolism. Sub-anticonvulsant CBD dose did NOT improve outcomes despite raising clobazam levels. Anticonvulsant CBD dose improved efficacy against both thermally-induced and spontaneous seizures.
How They Did This
Multi-method preclinical study: in vitro enzyme inhibition assays, mouse pharmacokinetic studies, the Scn1a+/- Dravet syndrome mouse model for seizure testing (thermally induced and spontaneous seizures), and Xenopus oocyte GABA receptor electrophysiology.
Why This Research Matters
Critics have suggested CBD's anti-seizure effect in clinical trials was just a side effect of boosting clobazam levels. This study refutes that claim by showing CBD has genuine anticonvulsant activity and a direct pharmacodynamic interaction with clobazam at GABA receptors.
The Bigger Picture
This study changes how we interpret CBD-clobazam clinical trial data. Rather than CBD being a passive drug interaction, the two compounds appear to have genuine therapeutic synergy through complementary mechanisms at GABA receptors.
What This Study Doesn't Tell Us
Mouse model of Dravet syndrome, while well-established, may not fully represent human disease. In vitro enzyme and receptor studies may not perfectly predict in vivo interactions. Specific dose translation to humans requires clinical confirmation.
Questions This Raises
- ?Should clobazam doses be specifically adjusted when combined with CBD to optimize the pharmacodynamic synergy?
- ?Does this dual mechanism explain why CBD appears more effective in patients already on clobazam?
- ?Are there other anti-epileptic drugs that might show similar synergy with CBD?
Trust & Context
- Key Stat:
- Two mechanisms, not just one
- Evidence Grade:
- Rated moderate because this uses multiple rigorous preclinical methods including a validated genetic model of Dravet syndrome, though human confirmation is still needed.
- Study Age:
- Published in 2019, after FDA approval of Epidiolex. Understanding the CBD-clobazam interaction remains clinically relevant.
- Original Title:
- Coadministered cannabidiol and clobazam: Preclinical evidence for both pharmacodynamic and pharmacokinetic interactions.
- Published In:
- Epilepsia, 60(11), 2224-2234 (2019)
- Authors:
- Anderson, Lyndsey L(10), Absalom, Nathan L(2), Abelev, Sarah V(3), Low, Ivan K, Doohan, Peter T, Martin, Lewis J, Chebib, Mary, McGregor, Iain S, Arnold, Jonathon C
- Database ID:
- RTHC-01912
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Does CBD really work for seizures or does it just boost other drugs?
Both. This study showed CBD genuinely enhances seizure control through its own anticonvulsant activity AND by boosting clobazam levels. A sub-therapeutic CBD dose raised clobazam levels but did not improve outcomes, proving the effect is not just about drug levels.
How do CBD and clobazam interact in the brain?
They both enhance GABA receptor activity, which is the brain's main inhibitory system. Together, they activate these receptors more than either drug alone, providing a synergistic anti-seizure effect.
Should medication doses be adjusted when using both?
The study confirms CBD increases clobazam blood levels by inhibiting its metabolism. Clinicians typically monitor clobazam levels and adjust doses when adding CBD, but the pharmacodynamic synergy suggests the combination itself has therapeutic value.
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Cite This Study
https://rethinkthc.com/research/RTHC-01912APA
Anderson, Lyndsey L; Absalom, Nathan L; Abelev, Sarah V; Low, Ivan K; Doohan, Peter T; Martin, Lewis J; Chebib, Mary; McGregor, Iain S; Arnold, Jonathon C. (2019). Coadministered cannabidiol and clobazam: Preclinical evidence for both pharmacodynamic and pharmacokinetic interactions.. Epilepsia, 60(11), 2224-2234. https://doi.org/10.1111/epi.16355
MLA
Anderson, Lyndsey L, et al. "Coadministered cannabidiol and clobazam: Preclinical evidence for both pharmacodynamic and pharmacokinetic interactions.." Epilepsia, 2019. https://doi.org/10.1111/epi.16355
RethinkTHC
RethinkTHC Research Database. "Coadministered cannabidiol and clobazam: Preclinical evidenc..." RTHC-01912. Retrieved from https://rethinkthc.com/research/anderson-2019-coadministered-cannabidiol-and-clobazam
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.