New evidence suggests that a chemical derived from marijuana may be an effective treatment for patients with drug-resistant forms of epilepsy

Charlotte Figi, an eight-year-old girl from Colorado with Dravet syndrome, a rare and debilitating form of epilepsy, came into the public eye in 2013 when news broke that medical marijuana was able to do what other drugs could not: dramatically reduce her seizures. Now, new scientific research provides evidence that cannabis may be an effective treatment for a third of epilepsy patients who, like Charlotte, have a treatment-resistant form of the disease.

Last month Orrin Devinsky, a neurologist at New York University Langone Medical Center, and his colleagues across multiple research centers published the results from the largest study to date of a cannabis-based drug for treatment-resistant epilepsy in The Lancet Neurology. The researchers treated 162 patients with an extract of 99 percent cannabidiol (CBD), a nonpsychoactive chemical in marijuana, and monitored them for 12 weeks. This treatment was given as an add-on to the patients’ existing medications and the trial was open-label (everyone knew what they were getting).

The researchers reported the intervention reduced motor seizures at a rate similar to existing drugs (a median of 36.5 percent) and 2 percent of patients became completely seizure free. Additionally, 79 percent of patients reported adverse effects such as sleepiness, diarrhea and fatigue, although only 3 percent dropped out of the study due to adverse events. “I was a little surprised that the overall number of side effects was quite high but it seems like most of them were not enough that the patients had to come off the medication,” says Kevin Chapman, a neurology and pediatric professor at the University of Colorado School of Medicine who was not involved in the study. “I think that [this study] provides some good data to show that it’s relatively safe—the adverse effects were mostly mild and [although] there were serious adverse effects, it’s always hard to know in such a refractory population whether that would have occurred anyway.”

http://www.scientificamerican.com/article/can-cannabis-treat-epileptic-seizures/