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New England Journal of Medicine Publishes Data on Purified CBD, Epidiolex, for People with Dravet Syndrome

Epilepsy News From: Wednesday, May 31, 2017

Recently, the New England Journal of Medicine (NEJM)1 published the results of a Phase 3 study of a purified cannabidiol (CBD) medication, called Epidiolex, in Dravet syndrome. The process used in this study is considered the “gold standard” method of determining if a medication of any kind is safe and useful.

“An important strength of this trial is that it was conducted as a randomized, double-blind, controlled clinical trial, which is the gold-standard methodology for determining the safety and efficacy of a potential new therapeutic,” said Brandy Fureman, vice president of research and new therapies for the Epilepsy Foundation. “Before publication of this trial, much of the clinical evidence about CBD's effects on people's seizures was uncontrolled and anecdotal.”

The company conducting the trial, Greenwich Biosciences (formerly called GW Pharmaceuticals), has taken a traditional drug development approach with this compound and are attempting to gain U.S. Food and Drug Administration (FDA) approval for Epidiolex. Currently, there are no FDA approved treatments for Dravet syndrome.

Limitations of the Study

  • This study was conducted only in children and young adults with Dravet syndrome, so it's not clear whether the effects will be the same in people with different forms of epilepsy. However, there are additional trials underway in other forms of epilepsy so more information about that question should be available soon.
  • CBD has an effect on how the body handles clobazam (Onfi), leading to substantially higher amounts of a breakdown product (nor-clobazam). Nor-clobazam can cause sleepiness, and some people will have to reduce the dose of clobazam as a result. More work in this area is needed to fully understand these drug-to-drug interactions.
  • With only 120 participants studied in total, it's possible that more rare side effects of CBD were not uncovered during the study.
  • CBD seemed to be helpful for some participants but not all participants, and this study is unlikely to be able to uncover why that was the case. Studying larger numbers of people over time will help, both to replicate these findings and to answer those additional questions as well.

What do these results mean?

  • The results show that overall people with Dravet syndrome taking Epidiolex had a 40% median reduction in seizures.
  • This means that people had a 40% drop in the number of seizures on Epidiolex compared to people getting placebo.
  • These results show that Epidiolex can be effective for some people with Dravet syndrome to reduce their seizures.
  • It is important to note that it did not work for everyone, but gives hope that a treatment option may be helpful and available for all people with Dravet syndrome if the FDA approves it.

Learn More


  1. Devinsky, Orrin; Cross, J. Helen; Laux, Linda; Marsh, Eric; Miller, Ian; Nabbout, Rima; Scheffer, Ingrid E.; Thiele, Elizabeth A.; Wright, Stephen. “Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome,” New England Journal of Medicine, May 25, 2017; 376(21):2011; http://www.nejm.org/doi/full/10.1056/NEJMoa1611618.

Authored by

Anup Patel MD

Reviewed Date

Wednesday, May 31, 2017

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