Taking a pharmaceutical formulation of cannabidiol, a cannabis-based medicine, cut seizures nearly in half for children with a rare and severe type of epilepsy called Dravet syndrome, according to a phase 3 study released today that will be presented at the American Academy of Neurology’s 71st Annual Meeting in Philadelphia, PA, May 4–10, 2019. Dravet syndrome, which starts in infancy, can lead to intellectual disability and frequent, prolonged seizures. Cannabidiol is derived from marijuana that does not include the psychoactive part of the plant that creates a “high.”

“It’s exciting to be able to offer another alternative for children with this debilitating form of epilepsy and their families,” said study author Ian Miller, MD, of Nicklaus Children’s Hospital, formerly Miami Children’s Hospital, in Florida. “The children in this study had already tried an average of four epilepsy drugs with no success and at the time were taking an average of three additional drugs, so to have this measure of success with cannabidiol is a major victory.”

The study involved 199 children (average age of 9) who were divided into three groups. One group received 20 milligrams per kilogram (mg/kg) per day of cannabidiol, the second group received 10 mg/kg per day, and the third group received a placebo.

Seizures were recorded for 4 weeks before the treatments were started to establish a baseline. Then the participants received the treatment for 14 weeks. By the end of the study, seizures with convulsions had decreased for those taking the high dose of the drug by 46% and by 49% for those taking the lower dose of the drug, compared to 27% for those taking the placebo.

Total seizures reduced by 47% for those in the high-dose group, by 56% for those in the lower-dose group, and by 30% for those in the placebo group. In the high-dose group, 49% of the participants had their seizures cut in half or more, compared to 44% in the low-dose group, and 26% in the placebo group.

All of the groups reported side effects, with 90% of the high-dose group, 88% of the low-dose group, and 89% of the placebo group. The most common side effects were decreased appetite, diarrhea, sleepiness, fever, and fatigue. About 25% of those in the high-dose group had serious side effects, compared to 20% percent of those in the low-dose group and 15% of those in the placebo group. Only participants in the high-dose group stopped taking the drug due to side effects; that number was 7%.

“Based on these results, dose increases above 10 mg/kg per day should be carefully considered based on the effectiveness and safety for each individual,” Miller said.

The study was supported by GW Research Ltd, developer of cannabidiol. In the United States, GW operates through its affiliate, Greenwich Biosciences, Inc.