"Evidence is mounting that a marijuanaderived oil might benefit some children with epilepsy whose seizures arent controlled by approved medications two new studies show. Cannabidiol CBD significantly reduced seizures in as many as half of children with epilepsy researchers planned to report Monday at the American Epilepsy Societys annual meeting in Philadelphia. But experts say these positive findings may have been influenced by a placebo effect. All participants in these studies knew they were taking the oil which could have affected reports of its effectiveness. We know that our placebo rates can be as high as  percent and sometimes higher said Dr. Amy BrooksKayal American Epilepsy Society president who wasnt involved in the studies. We dont know the real effect of the cannabidiol and we wont until we complete the studies that are ongoing that are placebocontrolled and blinded added BrooksKayal who is also a professor of pediatrics neurology and pharmaceutical sciences at the University of Colorado School of Medicine. There also are concerns that cannabidiol may interact badly with some antiseizure medications approved for epilepsy treatment according to another study scheduled for presentation at the meeting. Cannabidiol is a major chemical component of marijuana said Dr. Orrin Devinsky a neurologist at NYU Langone Medical Centers Comprehensive Epilepsy Center in New York City and coauthor of one of the studies. CBD doesnt produce intoxication like pots other major chemical compound THC. But researchers believe it may interact with a brain receptor that plays a role in the development of seizures Devinsky said. This receptor has several effects but one of them may be to modulate the calcium inside and outside the neuron which is very much related to the excitability of nerve cells he explained. Previous studies have shown some benefit in adults and word has spread. Families with adults and children with epilepsy have flocked to states where medical marijuana is legal to seek treatment BrooksKayal said. There is a fairly active and vocal group of families in Colorado who are using cannabidiol oils that are made artisanally she said. To see whether children with epilepsy would benefit from cannabidiol treatment Devinsky led a study involving  people mostly children whose seizures had not been controlled using current antiseizure medications. The average age of the participants was . Everyone received a Britishmade cannabidiol oil called Epidiolex which was administered as a drop on the tongue Devinsky said. This was in addition to their current drug therapy. After three months seizure frequency declined by an average  percent in all participants. Almost half experienced a  percent or greater reduction in seizures and about one of every  patients became seizurefree the study found. This was a very very treatmentresistant group and the response was very promising Devinsky said. A second study from the University of California San Francisco explored the longterm effectiveness of cannabidiol for children with epilepsy by adding the marijuanaderived oil to the regular drug regimen of about  kids for one year. The study found that after a year the treatment resulted in a  percent reduction in seizures for  participants  about  percent of the group. One child remained seizurefree but  of the initial participants dropped out of the study because the cannabidiol didnt seem to do them any good. Although he said he would prescribe CBD to people with uncontrolled seizures Devinsky said he is very anxious to see the results of ongoing randomized controlled clinical trials. The results of one major trial are expected in the first quarter of  he added. If CBD proves effective in controlled trials it could be two to five years before the drug is approved by the U.S. Food and Drug Administration Devinsky noted. Federal regulators also will have to weigh potential interactions of cannabidiol with other antiseizure drugs. Another study scheduled for presentation at the meeting found that CBD appeared to enhance the effects of the epilepsy medication levetiracetam Keppra when given to lab mice. However the oil appeared to interact negatively with two other drugs clobazam Onfi and carbamazepine Tegretol the University of Utah researchers found. Data and conclusions presented at meetings should be considered preliminary until published in a peerreviewed medical journal. More information For more on medical marijuana visit the U.S. National Institute on Drug Abuse http SOURCES Amy BrooksKayal M.D. American Epilepsy Society president and professor pediatrics neurology and pharmaceutical sciences University of Colorado School of Medicine Denver Orrin Devinsky M.D. neurologist NYU Langone Medical Center Comprehensive Epilepsy Center New York City Dec.   presentations American Epilepsy Society annual meeting Philadelphia"