Initial data from an open-label study in treatment-resistant epilepsy of pharmaceutical-grade cannabidiol — the nonpsychoactive ingredient in marijuana that is believed to be responsible for its antiepileptic action — suggest that it reduces seizure rate by about 30%.
The product, said to be 98% pure cannabidiol, in development under the brand name Epidiolex by GW Pharmaceuticals, which funded this study, was associated with a greater than 50% reduction in seizures in 39% of patients.
Lead investigator, Orrin Devinsky, MD, New York University School of Medicine, said he thought the results were “encouraging.”
“There appears to be potential for real benefit,” he told Medscape Medical News.
A second study of patients using many different types of medical marijuana has found not dissimilar results, with one third of patients reporting a seizure reduction of 50% or more.
The author of that study, Kevin Chapman MD, University of Colorado, Aurora, said this response rate was well below that expected from previous media reports. “There has been much discussion on the Internet and in the media about how medical marijuana is a miracle and children having the most intractable forms of epilepsy are becoming seizure-free,” he said. “But our data suggests that it is not as effective as these reports have suggested.”
The two studies will be presented at the American Epilepsy Society (AES) 68th Annual Meeting in December, but preliminary data have been released early by the organization.
Coauthor of the cannabidiol study, Daniel Friedman, MD, NYU Comprehensive Epilepsy Center, summarized the findings. “My feeling is that we still don’t know for sure if cannabidiol it is an effective treatment but our results do look promising and support further studies. While it probably won’t be the miracle that some advocates have claimed, I believe it will have a role for treating very difficult epilepsy cases.”
Dr Devinsky added: “The populations we are testing this drug on are notoriously difficult to treat. Any drug that has a beneficial effect is potentially very helpful. Most current epilepsy drugs are ineffective and have serious side effects. There is a huge unmet need.”
Dr Friedman pointed out that Dr Chapman’s study was particularly difficult to interpret because there was a huge variability in what the patients were taking.
“They were using medical marijuana from various sources,” he said. “This would be a very heterogeneous group of products. There are many different strains of medical marijuana. Some are claimed to have a high cannabidiol content but not all have independent laboratory verification or consistency from batch to batch. In contrast, in our study we were giving a pharmaceutical grade product — we know exactly what it contains and what dose the patient is getting. So our results are much more reliable.”
Dr Chapman agreed with this comment but said his research was interesting because it was the first study to report any results with medical marijuana. “This is really an unknown area of research. Many people are using these products and we wanted to see if they are actually helpful or not.”
KEEP READING: http://www.medscape.com/viewarticle/833770