The cannabis derivative cannabidiol reduced seizure frequency by 39 percent for patients with Dravet syndrome, a rare severe form of epilepsy. After years of anecdotal claims about its benefits, this was the first large-scale randomized clinical trial for the compound.
“Cannabidiol should not be viewed as a panacea for epilepsy, but for patients with especially severe forms who have not responded to numerous medications, these results provide hope that we may soon have another treatment option. We still need more research, but this new trial provides more evidence than we have ever had of cannabidiol’s effectiveness as a medication for treatment-resistant epilepsy,”
says lead investigator Orrin Devinsky, MD, professor of neurology, neurosurgery, and psychiatry and director of the Comprehensive Epilepsy Center at NYU Langone Medical Center.
Cannabidiol, or CBD, is a compound in the cannabis plant that does not contain psychoactive properties that induce a high. The study included a liquid pharmaceutical formulation of CBD, called Epidiolex, which is manufactured by GW Pharmaceuticals and has not been approved by the U.S. Food and Drug Administration. GW Pharmaceuticals funded the clinical trial.
Lowered Seizure Frequency
The study involved 120 children and adolescents with Dravet Syndrome between the ages of 2 and 18. Participants were randomized across 23 sites in the United States and Europe to receive either CBD 20 mg/kg or placebo added to their existing treatment over a 14-week period. Seizure frequency was tracked for one month prior to the study for baseline readings, and during the course of the study.
Specifically, seizure frequency dropped in the CBD-treated group by 39 percent from a median of nearly 12 convulsive seizures per month before the study to about six; three patients’ seizures stopped entirely.
In the placebo group, there was a 13 percent reduction in seizures from about 15 monthly seizures to fourteen. The difference in the degree of seizure reduction between the CBD group and the placebo group was both statistically significant and clinically consistent.
Side effects – experienced by 93.4 percent of patients in the CBD group and 74.6 percent of those treated with placebo – were generally reported as mild or moderate in severity. The most common side effects in the CBD group were vomiting, fatigue and fever.
Eight participants from the CBD group withdrew from the trial due to side effects compared to one participant in the placebo group.
Future research will look at whether safety and tolerability might be improved and whether efficacy of CBD can be maintained at lower doses. Longer term studies of CBD for Dravet Syndrome as well as for other forms of treatment-resistant epilepsy are also underway.
Orrin Devinsky, M.D., J. Helen Cross, Ph.D., F.R.C.P.C.H., Linda Laux, M.D., Eric Marsh, M.D., Ian Miller, M.D., Rima Nabbout, M.D., Ingrid E. Scheffer, M.B., B.S., Ph.D., Elizabeth A. Thiele, M.D., Ph.D., and Stephen Wright, M.D. Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome N Engl J Med 2017; 376:2011-2020May 25, 2017DOI: 10.1056/NEJMoa1611618