the component of cannabis that makes people high in larger quantities, researchers reported.
“THC can contribute to seizure control and mitigation some of the side effects of CBD,” said study coauthor and Austin, Tex., child neurologist Karen Keough, MD, in an interview. Dr. Keough and colleagues presented their findings at the 50th annual meeting of the Child Neurology Society.
In a landmark move, the Food and Drug Administration approved Epidiolex in 2018 for the treatment of seizures in two rare forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome. The agency had never before approved a drug with a purified ingredient derived from marijuana.
CBD, the active ingredient in Epidiolex, is nonpsychoactive. The use in medicine of THC, the main driver of marijuana’s ability to make people stoned, is much more controversial.
Dr. Keough said she had treated 60-70 children with CBD, at the same strength as in Epidiolex (100 mg), and 5 mg of THC before the drug was approved. “I was seeing some very impressive results, and some became seizure free who’d always been refractory,” she said.
When the Epidiolex became available, she said, some patients transitioned to it and stopped taking THC. According to her, some patients fared well. But others immediately experienced worse seizures, she said, and some developed side effects to Epidiolex in the absence of THC, such as agitation and appetite suppression.
Combination therapy
For the new study, a retrospective, unblinded cohort analysis, Dr. Keough and colleagues tracked patients who received various doses of CBD, in some cases as Epidiolex, and various doses of THC prescribed by the Texas Original Compassionate Cultivation dispensary, where she serves as chief medical officer.
The initial number of patients was 212; 135 consented to review and 10 were excluded for various reasons leaving a total of 74 subjects in the study. The subjects, whose median age at the start of the study was 12 years (range, 2-25 years), were tracked from 2018 to2021. Just over half (55%) were male, and they remained on the regimen for a median of 805 days (range, 400-1,141).
Of the 74 subjects, 45.9% had a reduction of seizures of more than 75%, and 20.3% had a reduction of 50%-75%. Only 4.1% saw their seizures worsen.
The THC doses varied from none to more than 12 mg/day; CBD doses varied from none to more than 26 mg/kg per day. O the 74 patients, 18 saw their greatest seizure reduction from baseline when they received no THC; 12 saw their greatest seizure reduction from baseline when they received 0-2 mg/kg per day of CBD.
Still controversial
Did the patients get high? In some cases they did, Dr. Keough said. However, “a lot of these patients are either too young or too cognitively limited to describe whether they’re feeling intoxicated. That’s one of the many reasons why this is so controversial. You have to go into this with eyes wide open. We’re working in an environment with limited information as to what an intoxicating dose is for a small kid.”
However, she said, it seems clear that “THC can enhance the effect of CBD in children with epilepsy” and reduce CBD side effects. It’s not surprising that the substances work differently since they interact with brain cells in different ways, she said.
For neurologists, she said, “the challenge is to find a reliable source of THC that you can count on and verify so you aren’t overdosing the patients.”
University of Saskatchewan, Saskatoon, child neurologist and cannabinoid researcher Richard Huntsman, MD, who’s familiar with the study findings, said in an interview that they “provide another strong signal that the addition of THC provides benefit, at least in some patients.”
But it’s still unclear “why some children respond best in regards to seizure reduction and side effect profile with combination CBD:THC therapy, and others seemed to do better with CBD alone,” he said. Also unknown: “the ideal THC:CBD ratio that allows optimal seizure control while preventing the potential harmful effects of THC.”
As for the future, he said, “as we are just scratching the surface of our knowledge about the use of cannabis-based therapies in children with neurological disorders, I suspect that the use of these therapies will expand over time.”
No study funding is reported. Dr. Keough disclosed serving as chief medical officer of Texas Original Compassionate Cultivation. Dr. Huntsman disclosed serving as lead investigator of the Cannabidiol in Children with Refractory Epileptic Encephalopathy study and serving on the boards of the Cannabinoid Research Initiative of Saskatchewan (University of Saskatchewan) and Canadian Childhood Cannabinoid Clinical Trials Consortium. He is also cochair of Health Canada’s Scientific Advisory Committee on Cannabinoids for Health Purposes.
