Medical marijuana for epilepsy: a pressing need for data

By Megan Brooks

NEW YORK (Reuters Health) - There is a pressing need for well controlled studies on the value of medical marijuana and pure cannabidiol (CBD) for severe forms of epilepsy, experts say in a new report.

Cannabis has been used to treat epilepsy for centuries, but data from double-blind randomized, controlled trials of CBD or THC in epilepsy are "lacking," Dr. Orrin Devinsky, Director of the Comprehensive Epilepsy Center at NYU Langone Medical Center in New York and Saint Barnabas Institute of Neurology and Neurosurgery in New Jersey, said in a statement.

A series of papers published online May 22 in Epilepsia looks at the potential use of marijuana and CBD in treating Dravet syndrome and other severe forms of epilepsy.

In one paper, Dr. Edward Maa, Chief of the Comprehensive Epilepsy Program at Denver Health in Denver, Colorado, and Paige Figi, mother of a child with Dravet syndrome, provide arguments from consumers and others that CBD and medical marijuana should be available now for the treatment of epilepsy.

Paige's daughter has Dravet syndrome. Through "exhaustive personal research and assistance from a Colorado-based medical marijuana group (Realm of Caring)," Paige started her daughter on adjunctive therapy with a strain of cannabis high in CBD and THC known as Charlotte's Web in conjunction with patient's antiepileptic drug regimen.

The addition of Charlotte's Web cut the child's seizure frequency from 50 convulsions per day to two to three nighttime convulsions per month, they report. "This effect has persisted for the last 20 months, and Charlotte has been successfully weaned from her other antiepileptic drugs," they note.

"Colorado is 'ground zero' of the medical marijuana debate," Dr. Maa notes in a statement. "As medical professionals it is important that we further the evidence of whether CBD in cannabis is an effective antiepileptic therapy."

Dr. Maria Roberta Cilio, Professor, Neurology and Pediatrics and Director of Pediatric Epilepsy Research at the University of California San Francisco and colleagues agree, noting in their paper that there is limited knowledge on the safety and utility of these compounds for epilepsy.

Adequate clinical trials are what's needed now, Dr. Cilio told Reuters Health by email. "Particularly, given the high biases associated with the use of cannabis-derivated products, randomized placebo-controlled trial are essential," she said.

In a critical review, Dr. Cilio, Dr. Devinksy and colleagues summarize current scientific evidence on CBD for epilepsy and other neurological or psychiatric disorders including anxiety, schizophrenia and addiction.

They note that THC, the primary psychoactive substance, and CBD, the main non-psychoactive ingredient in cannabis, show anticonvulsive properties in animals. However, the studies were conducted in acute animal models and data are limited for chronic recurrent seizures. More recent anecdotal reports of medical marijuana with high ratios of CBD to THC "have claimed efficacy, but studies were not controlled," they point out.

They add, "CBD bears investigation in epilepsy and other neuropsychiatric disorders, including anxiety, schizophrenia, addiction, and neonatal hypoxic-ischemic encephalopathy. However, we lack data from well-powered double-blind randomized, controlled studies on the efficacy of pure CBD for any disorder. Initial dose-tolerability and double-blind randomized, controlled studies focusing on target intractable epilepsy populations such as patients with Dravet and Lennox-Gastaut syndromes are being planned. Trials in other treatment-resistant epilepsies may also be warranted."

What are clinicians and parents to do in the meantime? Reuters Health asked Dr. Cilio, who said: "Medical marijuana is a term used to define different artisanal compounds which composition is often unknown. My view is that you should know the exact composition of the compound that you prescribe to a patient, especially a child, and that the use of this compound should be approved by FDA."

In an editorial, Drs. Gary Mathern and Astrid Nehlig, Editors-in-Chief of Epilepsia, and Associate Editor Dr. Michael Sperling, say, "Rarely in recent memory has there been such interest and public discussion about the potential use marijuana and one of its active substances cannabidiol (CBD) in the treatment of various neurologic conditions such as chronic pain and multiple sclerosis. This has been especially true for patients with refractory seizures and catastrophic epilepsies such as Dravet's syndrome."

The Editors would like to get feedback on this issue from patients, clinicians, and medical professionals and have posted a questionnaire at: http://surveys.verticalresponse.com/a/show/1539433/ea840f4206/0.

SOURCES: http://bit.ly/1tta6Y4, http://bit.ly/1gWttGT, http://bit.ly/1pj1yAy, and http://bit.ly/1k1mSpb

Epilepsia 2014.

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