- Last Updated on 19 December 2014
With recent legislation across the United States, there has been renewed interest in the therapeutic potential of marijuana (cannabis) for myriad conditions including epilepsy, and even infantile spasms. To a limited extent, this has been inspired by small studies in animals suggesting that cannabis may have anti-seizure properties, and early results of a recent open-label study exploring the effectiveness and safety of purified cannabidiol (CBD) for treatment of children with severe forms of epilepsy. The overwhelming source of enthusiasm has been from online parent testimonials and press reports of success in individual patients. However, like many "alternative" therapies which are outside mainstream medicine, there is limited scientific support for the use of cannabis to treat epilepsy. Although the internet is replete with testimonials extolling the virtue of medical marijuana, there is insufficient evidence—and especially safety data—to recommend its use for treatment of seizures in most cases. Please see our discussion of "Treatment X". However, for patients who have not responded to first-line mainstream therapies, and for whom the potential benefit and risks of ongoing seizures/spasms outweigh the largely unknown risks of marijuana therapy, a marijuana preparation may be a reasonable treatment. This should take place only after a candid and thorough conversation with a neurologist who is familiar with these therapies and associated risk.
It is particularly dangerous to try these therapies without informing your child's physicians, especially those who prescribe other drugs. Most readily available formulations of medical marijuana contain numerous—nearly 100—chemicals derived from the plant, many of which may interact with mainstream medications. Potential drug-interactions between cannabis and traditional anti-seizure medications are largely unknown. Particular caution should be exercised when giving marijuana products together with benzodiazepines, including clobazam (Onfi®, Frisium®), clonazepam (Klonopin®) and others, as well as felbamate (Felbatol®), valproate (Depakote®), carbamazepine (Tegretol®), oxcarbazepine (Trileptal®), perampanel (Fycompa®), prednisolone, primidone (Mysoline®), rufinamide (Banzel®), stiripentol (Diacomit®), tiagabine (Gabatril®), and zonisamide (Zonegran®).
In most countries, including the United States, there are many indirect and legal risks that accompany the use of marijuana preparations obtained in the community without oversight by regulatory agencies such as the Food and Drug Administration (FDA) and Drug Enforcement Agency (DEA). In the United States, although medicinal and recreational marijuana use is legal in many states, marijuana continues to be classified as a schedule I controlled substance and is illegal according to federal law. Therefore, children, parents, "prescribing" physicians, and "manufacturers" (growers/distributors) of marijuana preparations in all states are potentially vulnerable to arrest and prosecution. Furthermore, the possession and administration of these products are expressly forbidden in most hospitals.
There are efforts underway to rigorously evaluate the potential usefulness of medical marijuana. Specifically, several active drugs derived from marijuana, especially CBD, are being investigated as a potential treatments of severe epilepsy in children, including infantile spasms. A purified form of CBD is being developed and tested by GW Pharma, and a synthetic form of CBD is being developed and tested by Insys. CBD contrasts with the principal psychoactive component of marijuana called tetrahydrocannabinol (THC). THC is thought to be the constituent most responsible for the "high" of marijuana and associated effects on appetite and potential effects on cognition (e.g. amotivational syndrome, paranoia, unmasking of latent psychosis, etc). THC, which is far more potent than CBD, may be "proconvulsant" in some settings, meaning that consumption of THC may provoke seizures. In a parallel effort—not regulated by the FDA—several manufacturers (growers) have been breeding plants with high CBD content and low THC content. CBD, and other cannabinoids including THC, can be extracted from these plants using a variety of methods to produce a liquid/oil preparation which can be consumed. Despite rather compelling and emotional reports in the media, there continue to be major concerns regarding effectiveness, safety, and quality control (esp. CBD/THC content, dose variation from batch to batch, shelf-life, pesticide content, infectious—especially fungus—contamination).
The potential value of CBD-enriched cannibis extracts and pharmaceutical CBD preparations was a focal point during the most recent annual meeting of the American Epilepsy Society in Seattle, Washington (Dec 2014). Among the presentations were the results of a survey administered on this website, discussed below:
EFFICACY AND SAFETY OF EPIDIOLEX (CANNABIDIOL) IN CHILDREN AND YOUNG ADULTS WITH TREATMENT-RESISTANT EPILEPSY: INITIAL DATA FROM AN EXPANDED ACCESS PROGRAM
Authors: Orrin Devinsky, Joseph Sullivan, Daniel Friedman, Elizabeth Thiele, Eric Marsh, Linda Laux, Julie Hedlund, Nicole Tilton, Judith Bluvstein and Maria Cilio
In this study, Dr. Devinsky and colleagues describe the experience of 23 patients (mostly children) with severe epilepsy who took a purified cannabidiol preparation (GW Pharma) for at least 3 months. 4 patients became seizure-free and almost 40% of patients exhibited at least a 50% reduction in seizures. Side effects were generally modest. Typical dosage of CBD was 20 to 25 mg/kg/day.
Authors: Raymond Zhou, Catherine Jacobson, Julius Weng, Emily Cheng, Johnson Lay, Phoebe Hung, Jason Lerner, Raman Sankar and Shaun Hussain
This study—conducted by UCLA investigators who manage this website—is a presentation of an online survey of parents who have administered CBD-enriched cannabis preparations to their children for the treatment of severe epilepsy, including many patients with infantile spasms. Among 200 respondents, 117 had actually administered CBD products to their children. 53 children suffered from infantile spasms and/or Lennox Gastaut syndrome. Over 90% reported reductions in seizure frequency, and 13% reported seizure-freedom. Reported side effects were modest. Among the minority of parents who were able and willing to report exact CBD dosage, the typical dose was 4 mg/kg/day (1.8 mg/pound/day). Dosage was not different among children with and without improvement.
Authors: Craig Press, Kelly Knupp and Kevin Chapman
In this report, Drs. Press, Knupp, and Chapman reviewed the medical records of 58 patients (mostly children) cared for at Children’s Hospital Colorado who received cannabis extracts for treatment of epilepsy. 48% reported improvement in seizures and 31% reported at least 50% reduction in seizure-frequency. Curiously, the reported response rate among children who had moved to Colorado to obtain cannabis extracts was far higher than reported response rates for children already living in Colorado (52% vs. 17%). Dosage data were not available.
These studies do not provide adequate evidence to conclude that pure CBD or CBD-enriched cannabis extracts are safe and effective. All investigators highlighted the need for well-designed clinical trials to properly evaluate the effectiveness and safety of these products. These studies demonstrated wide discrepancies in response rate, and none were able to control for the impact of bias (e.g. placebo-like effects). Despite the favorable response rates in the studies of Devinsky and Zhou, it is still quite possible that CBD is ineffective and unsafe. The fantastically high response rates observed by Zhou et al and the observation of Press et al that patients who moved to Colorado were substantially more likely to report benefit suggests that response rates are highly vulnerable to bias; all response rates to date should be interpreted with extreme caution.