Researchers say the recently completed trial of Epidiolex is the first placebo-controlled trial to show treatment with cannabidiol, an extract from the marijuana plant that does not contain THC, works for patients with seizures, and it may lead to FDA approval. Photo: Atomazul / Shutterstock

WASHINGTON, March 14 (UPI) -- The marijuana-based drug Epidiolex significantly reduced seizures in children with Dravet syndrome in a phase 3 clinical trial, lending scientific credence to a treatment used for several years but mostly supported by anecdotal evidence.

GW Pharmaceuticals, which developed the drug, announced the results of the first of four trials with marijuana extract drugs it is conducting in the United States as it seeks approval from the Food and Drug Administration.


Epidiolex is made from cannabidiol, an extract that does not intoxicate people, but has been shown in individual uses to reduce seizures in children with the rare Dravet syndrome.

The condition develops early in life and can lead to tens of seizures per month, if not many more. Parents have flocked to Colorado and other states with medicinal marijuana to buy the extract, and several states have debated the legalization of Charlotte's Web, a strain of marijuana with very low levels of THC, the substance in pot that gets users high.

"In light of this positive data, we will now request a pre-NDA meeting with the FDA to discuss our proposed regulatory submission," Justin Gover, chief executive officer of GW Pharmaceuticals, said in a press release. "We also look forward with excitement to the upcoming results from the two Phase 3 trials in Lennox-Gastaut syndrome and the second pivotal trial in Dravet syndrome."

For the trial, researchers gave 120 patients either Epidiolex or placebo, in addition to other anti-epileptic drug treatments. The participants were an average of 10 years old, and 33 percent were under age 6, and the children had a median 13 seizures per month.

The researchers report a 39 percent reduction in seizures for children on Epidiolex and a 13 percent reduction for those on a placebo. The difference in efficacy of Epidiolex was seen after about a month of treatment, they said.

An additional phase 3 trial with 150 patients is ongoing, the company said, as are two trials for the drug with Lennox-Gastaut syndrome patients. A trial for people with tuberous sclerosis complex is also in the planning stages.

If approved, Epidiolex would be the first marijuana-based drug approved by the FDA.

The results are similar to those Dr. Orrin Devinsky, a researcher at New York University's Langone Medical Center, has found in previous studies, though they were not clinical trials for specific drugs.

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"The results of this Epidiolex pivotal trial are important and exciting as they represent the first placebo-controlled evidence to support the safety and efficacy of pharmaceutical cannabidiol in children with Dravet syndrome, one of the most severe and difficult-to-treat types of epilepsy," Devinsky said.