Meta-analysis of 4 RCTs confirms CBD reduces seizures with and without clobazam co-treatment
A stratified meta-analysis of four large RCTs confirmed CBD (Epidiolex) significantly reduced seizures regardless of clobazam co-use, though the effect was larger with clobazam and certain side effects increased with the combination.
Quick Facts
What This Study Found
CBD vs. placebo seizure reduction: treatment ratio 0.59 (p < .0001) with clobazam, 0.85 (p = .0226) without clobazam. 50% responder rate odds ratio: 2.51 (p < .0001) with clobazam, 2.40 (p = .0020) without. Somnolence, rash, pneumonia, and aggression were more common with concomitant clobazam.
Key Numbers
With clobazam: treatment ratio 0.59 (p < .0001), 50% responder OR 2.51. Without clobazam: treatment ratio 0.85 (p = .0226), 50% responder OR 2.40. AEs higher with clobazam for somnolence, rash, pneumonia, aggression.
How They Did This
Stratified meta-analysis of 4 large RCTs (2 Lennox-Gastaut, 2 Dravet syndrome) evaluating CBD 10 and 20 mg/kg/day. Results stratified by clobazam use. Negative binomial regression and logistic regression used. Pharmacokinetic exposure-response analysis included.
Why This Research Matters
A persistent question has been whether CBD's seizure benefit depends on its interaction with clobazam rather than direct anticonvulsant effects. This meta-analysis demonstrates independent efficacy.
The Bigger Picture
This resolves a critical clinical question: CBD has genuine anticonvulsant effects independent of clobazam, though the combination may provide additional benefit. Clinicians can now confidently prescribe CBD to patients not taking clobazam.
What This Study Doesn't Tell Us
Post-hoc stratified analysis of existing trials, not prospective; the difference in treatment ratios with/without clobazam could reflect a synergistic effect; cannot fully exclude confounding by clobazam indication.
Questions This Raises
- ?Is there a true synergistic effect between CBD and clobazam?
- ?Would patients do better adding clobazam to CBD vs. CBD alone?
Trust & Context
- Key Stat:
- CBD reduced seizures vs. placebo both with clobazam (p < .0001) and without (p = .023)
- Evidence Grade:
- Meta-analysis of 4 large, well-designed RCTs with stratified analysis and pharmacokinetic data.
- Study Age:
- Published in 2020.
- Original Title:
- Cannabidiol efficacy independent of clobazam: Meta-analysis of four randomized controlled trials.
- Published In:
- Acta neurologica Scandinavica, 142(6), 531-540 (2020)
- Authors:
- Devinsky, Orrin(9), Thiele, Elizabeth A(7), Wright, Stephen(6), Checketts, Daniel, Morrison, Gilmour, Dunayevich, Eduardo, Knappertz, Volker
- Database ID:
- RTHC-02511
Evidence Hierarchy
Combines results from multiple studies to find an overall pattern.
What do these levels mean? →Frequently Asked Questions
Does CBD only work because of its interaction with clobazam?
No. This meta-analysis shows CBD significantly reduced seizures even in patients not taking clobazam. The 50% responder rate was similar with or without clobazam (OR 2.51 vs. 2.40), confirming CBD has independent anticonvulsant effects.
Should CBD be combined with clobazam for best results?
The seizure frequency reduction was somewhat larger with clobazam co-treatment, suggesting possible added benefit. However, the combination also increased side effects like somnolence and rash. The decision should weigh individual patient factors.
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Cite This Study
https://rethinkthc.com/research/RTHC-02511APA
Devinsky, Orrin; Thiele, Elizabeth A; Wright, Stephen; Checketts, Daniel; Morrison, Gilmour; Dunayevich, Eduardo; Knappertz, Volker. (2020). Cannabidiol efficacy independent of clobazam: Meta-analysis of four randomized controlled trials.. Acta neurologica Scandinavica, 142(6), 531-540. https://doi.org/10.1111/ane.13305
MLA
Devinsky, Orrin, et al. "Cannabidiol efficacy independent of clobazam: Meta-analysis of four randomized controlled trials.." Acta neurologica Scandinavica, 2020. https://doi.org/10.1111/ane.13305
RethinkTHC
RethinkTHC Research Database. "Cannabidiol efficacy independent of clobazam: Meta-analysis ..." RTHC-02511. Retrieved from https://rethinkthc.com/research/devinsky-2020-cannabidiol-efficacy-independent-of
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.