Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome

BACKGROUND The Dravet syndrome is a complex childhood epilepsy disorder that is associated with drug‐resistant seizures and a high mortality rate. We studied cannabidiol for the treatment of drug‐resistant seizures in the Dravet syndrome. METHODS In this double‐blind, placebo‐controlled trial, we randomly assigned 120 children and young adults with the Dravet syndrome and drug‐resistant seizures to receive either cannabidiol oral solution at a dose of 20 mg per kilogram of body weight per day or placebo, in addition to standard antiepileptic treatment. The primary end point was the change in convulsive‐seizure frequency over a 14‐week treatment period, as compared with a 4‐week baseline period. RESULTS The median frequency of convulsive seizures per month decreased from 12.4 to 5.9 with cannabidiol, as compared with a decrease from 14.9 to 14.1 with placebo (adjusted median difference between the cannabidiol group and the placebo group in change in seizure frequency, ‐22.8 percentage points; 95% confidence interval [CI], ‐41.1 to ‐5.4; P=0.01). The percentage of patients who had at least a 50% reduction in convulsive‐seizure frequency was 43% with cannabidiol and 27% with placebo (odds ratio, 2.00; 95% CI, 0.93 to 4.30; P=0.08). The patient's overall condition improved by at least one category on the seven‐category Caregiver Global Impression of Change scale in 62% of the cannabidiol group as compared with 34% of the placebo group (P=0.02). The frequency of total seizures of all types was significantly reduced with cannabidiol (P=0.03), but there was no significant reduction in nonconvulsive seizures. The percentage of patients who became seizure‐free was 5% with cannabidiol and 0% with placebo (P=0.08). Adverse events that occurred more frequently in the cannabidiol group than in the placebo group included diarrhea, vomiting, fatigue, pyrexia, somnolence, and abnormal results on liver‐function tests. There were more withdrawals from the trial in the cannabidiol group. CONCLUSIONS Among patients with the Dravet syndrome, cannabidiol resulted in a greater reduction in convulsive‐seizure frequency than placebo and was associated with higher rates of adverse events. (Funded by GW Pharmaceuticals; ClinicalTrials.gov number, NCT02091375.)