A study found cannabidiol, a drug derived from marijuana, was effective at treating patients with treatment-resistant epilepsy. Photo courtesy of GW Pharmaceuticals

Aug. 13 (UPI) -- Cannabidiol, a drug derived from marijuana, was effective at treating patients with treatment-resistant epilepsy.

Researchers at the University of Alabama at Birmingham found that cannabidiol, or CBD oil, reduced the number of seizures among patients who did not respond to traditional treatments. Their findings were published last week in the journal Epilepsy and Behavior.


On June 25, the U.S. Food and Drug Administration approved Epidiolex to treat seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome. It was the first FDA approval of a purified drug derived from cannabis.

The purified oil contains only trace amounts of THC, which is the psychotropic component of cannabis.

"The results are particularly interesting since, rather than enrolling patients with a specific diagnosis, we enrolled patients of all ages with various treatment-resistant epilepsies, indicating that CBD oil may be effective across the spectrum of epileptic conditions," Dr. Martina Bebin, a professor in the Department of Neurology in the School of Medicine at UAB, said in a press release.

In 2015, the study was launched after the Alabama legislature approved Carly's Law, which authorized the UAB Epilepsy Center and Children's of Alabama to conduct research with cannabidiol. The legislation is named after Carly Chandler, who has a rare genetic disorder called CDKL5 and uses the marijuana-derived medication.

The research included 132 patients -- 72 children and 60 adults -- whose data, including diaries, were examined from medical visits at 12, 24 and 48 weeks.

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Seizure frequency among participants decreased from 144 seizures every two weeks to 52 seizures over two weeks during the first 12 weeks of the study, and the decrease remained stable throughout the 48-week study.

"This is a highly significant reduction in the number of seizures that the majority of patients experienced, nearly a two-thirds reduction across the entire study population," Bebin said. "Some patients experienced an even greater reduction of seizure frequency."

In addition, patients were measured on an adverse events profile score. The AEP decreased from 40.8 at the beginning of CBD therapy to 33.2 at 12 weeks.

In terms of overall severity of seizures, patients scores on the Chalfont Seizure Severity Scale decreased from 80.7 at the start to 39.2 at 12 weeks.

Scores remained stable at the 48-week mark in both measures.

"An improvement of 10 points or more on the CSS Scale is clinically significant," principal investigator Dr. Jerzy Szaflarski, director of the UAB Epilepsy Center, said.

He noted there was as much as a 50 percent to 60 percent improvement, and the researchers found few side effects among participants during treatment

"Perhaps more importantly, the AEP scores remained stable throughout the study period despite further increases in CBD dosing and decreases in other anti-seizure medications," Szaflarski said. "Of note is that only two participants in the pediatric and two in the adult portions of the study withdrew because of adverse events alone."