After years of anecdotal claims about its benefits, the cannabis derivative cannabidiol (CBD) has been shown to reduce seizure frequency by 39% in patients with Dravet syndrome—a rare, severe form of epilepsy—in the first large-scale, randomized clinical study of the compound. The New England Journal of Medicine published the findings online on May 24.
“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,” said lead investigator Orrin Devinsky, MD, professor of neurology, neurosurgery, and psychiatry at the NYU Langone Medical Center. “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.”
CBD is a compound in the cannabis plant that does not contain psychoactive properties that induce a high. The study involved an investigational liquid formulation of CBD called Epidiolex (GW Pharmaceuticals).
A total of 120 children and adolescents between the ages of 2 and 18 years with Dravet syndrome were randomly assigned to receive either CBD 20 mg/kg or placebo, which was added to their existing treatment during a 14-week period. Seizure frequency was tracked for one month before the study for baseline readings and during the course of the study.
Seizure frequency dropped 39% in the CBD-treated group, from a median of nearly 12 convulsive seizures per month before the study to approximately six; three patients’ seizures stopped entirely. The placebo group showed a 13% reduction in seizures from approximately 15 monthly seizures to 14. The difference in the degree of seizure reduction between the CBD group and the placebo group was statistically significant.
Adverse events, experienced by 93% of subjects in the CBD group and by 75% of those in the placebo group, were generally mild or moderate in severity. The most common adverse events in the CBD group included vomiting, fatigue, and fever. Eight subjects in the CBD group withdrew from the trial because of adverse events compared with one subject in the placebo group.
GW Pharmaceuticals plans to file its cannabis-derived drug Epidiolex with the FDA by mid-year. The medication, which is administered as a syrup, contains less than 0.1% of tetrahydrocannabinol, the substance that makes people high.
GW is seeking regulatory approval to sell Epidiolex as a treatment for both Dravet syndrome and Lennox–Gastaut syndrome, another severe form of epilepsy.