CBD interacts with at least 15 anti-seizure medications through multiple mechanisms
A review of 30 studies found cannabidiol has pharmacokinetic interactions with at least 15 anti-seizure medications (including clobazam, valproate, and topiramate) and pharmacodynamic interactions with three, primarily through the cytochrome P450 system.
Quick Facts
What This Study Found
CBD has potential pharmacokinetic interactions with brivaracetam, clobazam, eslicarbazepine, lacosamide, gabapentin, oxcarbazepine, phenobarbital, potassium bromide, pregabalin, rufinamide, sirolimus/everolimus, stiripentol, tiagabine, topiramate, and zonisamide. Pharmacodynamic interactions were identified for clobazam, valproate, and levetiracetam. Animal data suggested brain drug concentrations may change while serum levels remain stable.
Key Numbers
30 studies identified; pharmacokinetic interactions with 15 ASMs; pharmacodynamic interactions with 3 ASMs; cytochrome P450 primarily implicated; animal data showed brain-serum concentration discordance
How They Did This
Narrative review of 30 studies (18 observational cohort, 2 RCTs, 3 case reports/series, 3 animal studies, 2 briefing reports, 1 cohort analysis, 1 clinical trial simulation) on CBD interactions with anti-seizure medications, identified through Cochrane, PubMed, and Embase searches (2015-2020).
Why This Research Matters
Since CBD is used adjunctively with other anti-seizure medications, understanding interactions is essential for safe prescribing. The finding that brain levels may change without serum level changes is particularly concerning for therapeutic drug monitoring.
The Bigger Picture
The breadth of CBD's drug interaction profile underscores that it is not a "gentle" supplement but a pharmacologically active compound requiring the same careful drug interaction management as any potent medication.
What This Study Doesn't Tell Us
Some interactions based on small cohorts or case reports. Narrative rather than systematic review. Drug interactions may vary with CBD dose, formulation, and individual patient metabolism. Animal brain-serum discordance finding needs human confirmation.
Questions This Raises
- ?Are clinicians adequately monitoring for CBD drug interactions in practice?
- ?How should therapeutic drug monitoring be modified when brain and serum levels may diverge?
Trust & Context
- Key Stat:
- CBD has pharmacokinetic interactions with at least 15 anti-seizure medications
- Evidence Grade:
- Comprehensive review of 30 studies covering multiple interaction mechanisms, though some interactions are based on limited evidence.
- Study Age:
- Published in 2021 reviewing studies from 2015-2020.
- Original Title:
- Interaction of cannabidiol with other antiseizure medications: A narrative review.
- Published In:
- Seizure, 86, 189-196 (2021)
- Database ID:
- RTHC-03154
Evidence Hierarchy
Summarizes existing research without a strict systematic method.
What do these levels mean? →Frequently Asked Questions
Which drug interactions are most concerning?
The clobazam interaction is the most clinically significant, as CBD raises levels of N-desmethylclobazam. Valproate interactions can cause liver enzyme elevations. The finding that brain drug levels may change without serum changes is also concerning for any co-prescribed medication.
Why does CBD interact with so many drugs?
CBD is metabolized by and inhibits multiple cytochrome P450 enzymes, which are the same enzymes that process many anti-seizure medications. This creates a broad interaction potential that requires careful monitoring when CBD is added to existing medication regimens.
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Cite This Study
https://rethinkthc.com/research/RTHC-03154APA
Gilmartin, Christopher G S; Dowd, Zoya; Parker, Alasdair P J; Harijan, Pooja. (2021). Interaction of cannabidiol with other antiseizure medications: A narrative review.. Seizure, 86, 189-196. https://doi.org/10.1016/j.seizure.2020.09.010
MLA
Gilmartin, Christopher G S, et al. "Interaction of cannabidiol with other antiseizure medications: A narrative review.." Seizure, 2021. https://doi.org/10.1016/j.seizure.2020.09.010
RethinkTHC
RethinkTHC Research Database. "Interaction of cannabidiol with other antiseizure medication..." RTHC-03154. Retrieved from https://rethinkthc.com/research/gilmartin-2021-interaction-of-cannabidiol-with
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.