A medicine based on cannabidiol, a non-psychoactive molecule found in cannabis, has been found to cut the number of seizures by half among some patients suffering from a severe form of epilepsy.
The results provide a boost for claims that cannabidiol, or CBD, can be an effective treatment for epileptic patients — a view supported by a growing body of evidence despite legal restrictions that have made it difficult for scientists to extensively study the substance, as well as reluctance so far among federal authorities to officially sanction use of the compound in medicine.
CBD, often referred as CBD oil, is already available over-the-counter in some states that have legalized its medicinal use, even though it is still considered an illegal substance by the federal Drug Enforcement Administration.
Meanwhile, the Food and Drug Administration is studying whether to approve CBD extract as medicine, while issuing formal warnings to makers of products containing CBD oil to stop making claims about the health benefits of their products.
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The results of the new study, presented Tuesday at the annual meeting of the American Academy of Neurology, add fuel to the assertion that CBD may soon gain acceptance as a powerful treatment for severe cases of epilepsy.
"Our study found that cannabidiol shows great promise in that it may reduce seizures that are otherwise difficult to control," said the author of the study, Dr. Anup Patel, of Nationwide Children's Hospital and The Ohio State University College of Medicine in Columbus.
The study looked at 225 patients with a severe form of epilepsy known as Lennox-Gastaut syndrome (LGS), who had an average of 85 drop seizures per month. On average, the patients had each already tried six epilepsy drugs that had proved ineffective, and were taking an average of three epilepsy drugs during the study.
A drop seizure occurs when a patient loses muscle control, usually for no more than 15 seconds.
Some participants were given a higher dose of 20 milligrams-per-kilogram of body weight of cannabidiol daily, while others were given a lower dose of 10 milligrams-per-kilogram. Others were given a placebo. All of the patients continued taking their current medications for the duration of the 14-week trial.
More than three-in-ten patients in the study experienced a 50 percent or more reduction in drop seizures when taking CBD, compared to a 15 percent drop in those taking the placebo.
Those taking the higher dose had a 42 percent reduction in drop seizures overall on average. Those taking the lower dose had a 37 percent reduction in drop seizures. For 36 percent of patients, seizures were reduced by half or more.
Those taking the placebo had a 17 percent reduction in drop seizures. For 15 percent of patients taking the placebo, seizures were reduced by half or more.
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The study follows a review of the available evidence published in the New England Journal of Medicine in late 2015 suggesting more research was needed on the question of whether CBD could be an effective treatment for epilepsy.
“The pharmacologic and biochemical features of cannabinoids make them candidates for antiseizure medications,” the authors of that study wrote. But, “at this time, anecdotes have outstripped controlled clinical trials as sources of support for their clinical value.”
Almost all patients in the study reported some side effects, ranging from 94 percent of those taking the higher dose to 72 percent of those taking the placebo. But most side effects reported were mild-to-moderate. The two most common side effects were decreased appetite and sleepiness.
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