26-06-2014 | Epilepsy Ireland statement on the use of cannabis in the treatment of epilepsy

26 June 2014
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Despite recent advances in the understanding and treatment of epilepsy, up to 30% of people living with the condition do not respond to existing anti-epileptic drugs (AEDs) and continue to experience regular, debilitating and potentially life-threatening seizures.

Much needed research to find new and better treatments is continuing around the world. In recent months, there has been a lot of discussion about the potential benefits of cannabis and its derivatives in treating epilepsy.

There appears to be anecdotal evidence from the US that cannabis can reduce seizures in some people. This is thought to be because of the non-psychoactive component of cannabis called cannabidiol (CBD). In addition to the anecdotal reports, a limited number of studies of CBD in animal models have shown anti-convulsant effects but the mechanism of action is not yet understood.

In the US, a number of states have legalised the use of medical marijuana and other states have introduced legislation to permit clinical trials of CBD under tight regulation. These trials, on an investigational drug called Epidolex, are currently underway. Epidiolex has not been approved for use by any national regulatory agency but has received orphan drug status in the US from the FDA for two rare but severe childhood epilepsy syndromes - Dravet Syndrome and Lennox-Gastaut Syndrome. An orphan drug is one that has been developed specifically to treat a rare medical condition. Manufacturers of orphan drugs are given certain incentives such as a streamlined route to approval in order to encourage the development of drugs which would otherwise not be economically viable.

While there have been some positive anecdotal accounts, there have also been reports of cannabis and CBD making seizures worse in children, as well as other negative side effects that have required hospitalisation. Animal studies have also highlighted the potential for CBD to be pro-convulsant (increasing the risk of a seizure) in some cases.

Currently, no robust evidence from high quality scientific studies exists to support the use of cannabis or CBD in epilepsy. Individual successful cases do not provide strong enough evidence to expose large amounts of people to unknown and unquantifiable risks. It is therefore neither possible nor ethical at this stage for Epilepsy Ireland to state whether cannabis or CBD is a safe and effective treatment for epilepsy.

Even if the results of the clinical trials show treatment potential, additional follow-up studies similar to those that all other effective treatments for epilepsy have undergone will be needed before it can be approved and licenced for use.

As an organisation that funds epilepsy research, Epilepsy Ireland welcomes all research that seeks to develop safe and effective treatments for epilepsy. We therefore welcome the ongoing efforts to establish whether cannabis or CBD may prove useful in the long term for people whose epilepsy does not respond to current treatments.

In Ireland, cannabis is currently a Schedule 1 drug covered under the Misuse of Drugs Acts which makes it an offence to be in possession of cannabis. The Act also prevents the use of medicinal products containing cannabis and its derivatives. Changes to the Act to allow the use of Sativex, a CBD-based drug for Multiple Sclerosis which has been approved by the Irish Medicines Board are in the pipeline. Should any epilepsy treatment containing CBD be approved for use in Ireland having undergone the required rigorous testing, Epilepsy Ireland will support the need for access to the drug for those who could benefit from its prescribing.

Further Information:

June 2014 issue of leading epilepsy medical journal Epilepsia

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