NEW ORLEANS – Cannabidiol-enriched oil (CBD) may reduce seizures in children and adults with treatment-resistant epilepsy, but about a third of patients develop tolerance, meaning the medication becomes less effective over time, suggests new research being presented at the American Epilepsy Society Annual Meeting.
While previous research has shown decreasing effectiveness of cannabinoids can develop when used for pain management and in the treatment of seizures in animals, this is the first large study to show it can occur in human epilepsy therapy with CBD. In the United States, one CBD medication is approved by the Food and Drug Administration (FDA) for use in children and adults for two rare forms of epilepsy, Dravet syndrome and Lennox-Gastaut syndrome. The medication is a purified molecule from the cannabis plant and does not contain THC, which causes a high. It is not the same as medical marijuana, which may contain THC, pesticides and other impurities.
The study was conducted in Israel and researchers used two CBD formations with a CBD/THC ratio of 20 to 1.
"CBD is a good option for children and adults with certain kinds of epilepsy, but as with anti-epileptic drugs (AEDs), it can become less effective over time and the dose may need to be increased to manage the seizures," said Shimrit Uliel-Sibony, M.D., lead author of the study and head of the pediatric epilepsy service at Tel Aviv Sourasky Medical Center's Dana-Dwek Children's Hospital, Israel.
The study included 92 children and adults (ages 1 to 37) with epilepsy whose seizures were not well-managed with AEDs and who used CBD for an average of 19.8 months. They had various forms of epilepsy ranging from Dravet syndrome and Lennox-Gastaut syndrome to epilepsy caused by stroke. Researchers determined 53 people (57 percent) experienced a 50 percent reduction in average monthly seizure frequency, meaning the treatment was considered effective. Of those 53, tolerance developed in 17 (32 percent) after an average of 7.3 months. Tolerance was defined as either the need to increase the dose by 30 percent or more to achieve the same benefit or a reduced response of more than 30 percent leading to increased seizures. The CBD dose was increased in all people who had developed tolerance: 12 achieved success and 15 did not benefit.
About a third of patients discontinued treatment due to lack of effectiveness or because of side effects, which included sleepiness and gastrointestinal issues such as nausea, decreased appetite, and vomiting. Two people experienced worse seizures and one showed signs of psychosis; in those three cases, the CBD treatment was stopped immediately.