Epilepsy and Medical Cannabis
Definition
Epilepsy is associated with abnormal electrical activity in the brain, which causes convulsions, loss of consciousness, sensory disturbances and, in some cases, sensitivity to lights, patterns and sounds.
Potential Efficacy / Quality of Evidence (Low, Average, High) of Medical Marijuana for Epilepsy
High – there is now significant evidence that CBD, CBDA, CBDV and THCA could be of particular use for those with Lennox-Gastaut Syndrome or Dravet Syndrome. The Food and Drug Administration (FDA) has also approved the use of the CBD-based, GW Pharmaceuticals-produced Epidiolex for epilepsy throughout the US. GR Pharmaceuticals are a UK-based company that make medications derived from phytocannabinoids, such as the UK-approved Sativex (for multiple sclerosis).
Cannabinoids, Terpenes/Terpenoids, Strains and Ratios that May Help
CBD, THCA, CBDV and CBDA could be of particular use for epilepsy. Small amounts of THC could be helpful, too.
CBD:THC 25:1; CBD:THC 20:1; CBD:THC 18:1; CBD:THC 1:1.
Medical Cannabis Pros
CBD may have anticonvulsant effects.
CBD may have antiepileptic effects.
Cannabinoids may help treat neuronal hyperexcitability.
Medical Cannabis Cons
CBD desensitizes the enzyme CYP450, meaning that it could interfere with the metabolism of many anti-epileptic drugs (AEDs).
CBD may not be suitable for all types of epilepsy, and may in some cases may make seizures worse. This may be the case with the cannabinoid THCV (or at least some of its analogues) as well.
There is some concern about the use of hemp-derived CBD products, mostly as many of them are not necessarily tested for safety and efficacy. Hemp is not the most readily-available source of cannabinoids (it is grown for materials and bioremediation). This means that the extraction methods may be rather harsh and leave solvent in the final product, the final product may contain heavy metals that are “sucked up” through the soil by the hemp plant and often not even contain the amount of CBD stated so on the label. There is also some concern that, by removing compounds such as THC, the product is not as effective as it could be.
More About the Condition
Even though it has become big news over the past several years, the idea that cannabis could help reduce the frequency of seizures has been around since the 1970s. Indeed, alongside glaucoma, cancer and multiple sclerosis (MS), epilepsy was one of the first conditions where cannabinoid-based treatments were thought to potentially have anti-seizure effects.
The initial researchers were correct, and there is now a considerable body of evidence suggesting that cannabidiol (CBD) can help reduce the frequency of seizures in people suffering from Dravet syndrome or Lennox-Gastaut syndrome. We now have the Schedule V, CBD-based Epidiolex available on prescription in the US.
If you read through all the conditions on this site, you will notice that there is one similar thing that binds them all: inflammation. Epilepsy is no different in this regard, where there are lesions found in the nervous system, and there is impaired regulation of the immune system in the injured neuronal tissue.
There are several reasons why CBD helps for some kinds of epilepsy. These include:
CBD desensitizes the TRPV1 receptor (aka the vanilloid receptor, responsible for detecting pain and heat), thereby reducing neuronal excitability.
CBD acts as an anti-inflammatory as “cannabinoids downregulate cytokine and chemokine production and, in some models, upregulate T-regulatory cells (Tregs) as a mechanism to suppress inflammatory responses.”
High concentrations of CBD block calcium ion channels and antagonizes CB1 and CB2 receptors, lending to CBD’s anticonvulsant properties.
“An effect on adenosine reuptake and antagonism of G protein-coupled receptor 55 (GPR55) have been recently suggested to play an important role in CBD anti-seizure activity.” Perucca, Emilio. ‘Cannabinoids in the Treatment of Epilepsy: Hard Evidence at Last?‘ Journal of epilepsy research vol. 7,2 61-76. 31 Dec. 2017, doi:10.14581/jer.17012
Cytochrome P450 (CYP450), CYP2C9, CYP3A, CYP2C19, and CYP2D6 are all enzymes that are responsible for the metabolism of many anti-epileptic drugs (AEDs), such as Clobazam. Many of those with epilepsy have mutations in the genes that code for these enzymes, meaning that the anti-epileptic drugs (AEDs) they are being given are not effective, and even harmful. Side-effects include addiction, drowziness, fatigue, tremors, headache. vomiting, being in a “fog” and, in cases of overdose, death. CBD could help reduce or replace the need for such drugs.
Quotes from Experts
“Evidence concerning the potential anti-seizure efficacy of cannabinoids reached a turning point in the last 12 months, with the completion of three high-quality placebo-controlled adjunctive-therapy trials of a purified CBD product in patients with Dravet syndrome and Lennox-Gastaut syndrome. In these studies, CBD was found to be superior to placebo in reducing the frequency of convulsive (tonic-clonic, tonic, clonic, and atonic) seizures in patients with Dravet syndrome, and the frequency of drop seizures in patients with Lennox-Gastaut syndrome. For the first time, there is now class 1 evidence that adjunctive use of CBD improves seizure control in patients with specific epilepsy syndromes.” Source: Perucca, Emilio, ibid.
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Case Studies – Patient Stories
Billy Caldwell and the Fight for Medical Cannabis in the UK | The Independent
