A clinical pharmacology review of Epidiolex (pure plant-derived CBD) found it reduced convulsive seizures in Dravet and drop seizures in Lennox-Gastaut by 17-23% over placebo, with important drug interactions with clobazam and valproate.
Prescribing neurologists, pharmacists, and families managing severe childhood epilepsy.
17-23% over placebo
What the researchers found
In the GWPCARE trial series, CBD reduced key seizure frequencies by 17-23% compared to placebo as adjunctive therapy in patients 2+ years old. Common adverse effects: somnolence, diarrhea, elevated liver enzymes. Important drug interactions with clobazam, valproates, and CYP2C19/3A4 inhibitors/inducers. This is the first cannabis-derived FDA-approved medication.
Why it matters
This clinical pharmacy-focused review provides the practical dosing, monitoring, and interaction information clinicians need to safely prescribe CBD for epilepsy, going beyond efficacy to address real-world implementation.
The numbers in context
Seizure reduction: 17-23% over placebo. Approved for patients 2+ years old. Key interactions: clobazam, valproates, CYP2C19 and CYP3A4 modulators. Adverse effects: somnolence, diarrhea, hepatic transaminase elevations.
How the study worked
Review of EMBASE and MEDLINE (1946-October 2018) plus product labeling and ClinicalTrials.gov for efficacy, safety, pharmacology, and pharmacokinetics of Epidiolex in Dravet and Lennox-Gastaut syndromes.
What this study cannot tell us
Approved for only two epilepsy syndromes. Long-term safety data still accumulating. Drug interactions complicate use in patients on multiple anti-epileptic drugs. Mechanism of action remains hypothesized, not confirmed.
How to read the evidence
Rated strong because the review is based on Phase III GWPCARE RCTs that led to FDA approval.
When this study was published
Published in 2019, shortly after FDA approval of Epidiolex.
The bigger picture
Epidiolex approval created a new category of prescription drug that requires clinicians to understand cannabinoid pharmacology. This review bridges the gap between the clinical trial data and day-to-day prescribing decisions.
Questions still open
- Will CBD gain approval for additional epilepsy syndromes? How should hepatic monitoring be optimized? Can drug interaction management be standardized?
Common questions
How effective is Epidiolex?
What drug interactions should be watched?
Read the original research
Cannabidiol: A New Hope for Patients With Dravet or Lennox-Gastaut Syndromes.
The Annals of pharmacotherapy, 53(6), 603-611
Citation
Chen, Jeffrey W; Borgelt, Laura M; Blackmer, Allison B. (2019). Cannabidiol: A New Hope for Patients With Dravet or Lennox-Gastaut Syndromes.. The Annals of pharmacotherapy, 53(6), 603-611. https://doi.org/10.1177/1060028018822124
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