A cannabis derivative appears to help prevent seizures.
Cannabidiol (CBD), a type of cannabinoid, has come into focus as a potential therapy for various conditions, including epilepsy.
CBD is looking promising for children with treatment-resistant forms of epilepsy, such as Lennox-Gastaut Syndrome (LGS) and Dravet Syndrome (DS).
Epidiolex, a pharmaceutical liquid formulation of CBD developed by GW Pharmaceuticals, is currently undergoing phase 3 clinical trials in the US, authorized by the US Food and Drug Administration (FDA).
Three studies highlighting the efficacy and safety of CBD were presented at the conference; a fourth discussed its possible interactions with existing anti-epileptic drugs (AEDs).
The largest study presented efficacy and safety data on Epidiolex over a 12-week period.
Cannabidiol treatment reduces seizures
The 261 participants, mostly children with an average age of 11 years, had severe epilepsy that had not responded adequately to other treatments.
Epidiolex was given in gradually increasing doses, alongside current AED treatment regimes, of which patients were taking an average of three.
Participants and their families/caregivers recorded the number of seizures before taking CBD and during the treatment.
Clinicians also tested hematologic, liver and kidney function as well as AED levels before treatment and then at 4, 8 and 12 weeks during the study.
After 3 months, the frequency of all seizures was a median of 45% lower in all participants; 47% experienced a 50% or greater reduction in seizures, and 9% of patients were seizure-free. Patients with DS experienced a 62% reduction in seizures, and 13% were seizure-free. Those with LGS saw a 71% reduction in atonic seizures.
More than 10% of participants experienced adverse effects, mainly sleepiness, diarrhea and fatigue, causing 4% of patients to discontinue treatment. Serious adverse events were reported in 34% of patients, of which 5% were considered treatment-related. These included altered liver enzymes, status epilepticus, diarrhea and others. Lack of efficacy led 12% to withdraw from the study.
Lead author Dr. Orrin Devinsky, of New York University Langone Medical Center's Comprehensive Epilepsy Center, says:
"We are pleased to report these promising data on significant numbers of children. These data reinforce and support the safety and efficacy we have shared in previous studies. Most importantly it is providing hope to the children and their families who have been living with debilitating seizures."
He notes, however, that as this was an uncontrolled study, further investigations are needed to confirm results. Randomized controlled studies, currently underway, should give a better understanding of the drug's effectiveness.
Long-term drug effectiveness
In a related study, Dr. Michael Oldham, of the University of Louisville in Kentucky, explored the long-term efficacy of Epidiolex by following 25 people from the previous study, with an average age of 9 years, for 1 year. As before, the patients took CBD with their regular AED regimen.
After 12 months, 10 participants saw a 50% reduction in seizures. One participant with DS remained seizure-free; 12 stopped using CBD because it did not work for them. One suffered a marked increase in seizure frequency due to CBD.
In the 12-week study, says Dr. Oldham, CBD as an add-on therapy caused a 50% reduction in seizures for 1 in 3 patients; this improvement continued in 40% of participants for the whole 12-month period. This, he says, shows "strong promise that CBD can be effective in controlling seizures."
A third preclinical study, conducted at the University of Utah, focused on the anticonvulsant and tolerability profile of CBD in animal models. Using the Anticonvulsant Screening Program (ASP), the researchers found that CBD exerted significant anticonvulsant effects and was well-tolerated in rodents.
A fourth study, led by Misty D. Smith, PhD, at the University of Utah, explored the interaction between CBD and five different AEDs in animal models of seizure: carbamazepine, valproate, levetiracetam, clobazam and lacosamide.
The interactions between these drugs could be additive, meaning the drugs work well together; synergistic, meaning they enhance each other; or antagonistic, where the combination of drugs reduces overall effectiveness.
Smith analyzed three fixed-dose ratio combinations of CBD with each AED to assess the effectiveness of each combination against limbic seizure activity.
A significant synergistic interaction was found between CBD and levetiracetam. Significant antagonistic interactions were noted with some combinations of CBD with clobazam and CBD with carbamazepine.
Smith comments that a better understanding of the nature of these interactions will help optimize therapeutic safety and efficacy for CBD in the future.
Marijuana plants used for medication are specially bred by scientists, who produce CBD in a suitable form for therapeutic purposes. This form of the drug is not intoxicating.
Medical News Today recently reported on the dangers of high-potency recreational cannabis.