02 June 2017
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Medicinal Cannabis in Epilepsy: Frequently asked questions

Last updated: 27th June 2018

The use of medicinal cannabis to treat certain types of epilepsy and other medical conditions has been a topical issue in recent times.

In this article, we will answer a number of the most frequently asked questions in what has become a complex, emotive and rapidly evolving issue. Links are given throughout to further information and a list of further reading, as well as some pdf documents are available at the end.

What is medicinal cannabis?

There are many different interpretations of what is meant by 'medicinal cannabis'. In general, the phrase "medicinal cannabis" does not refer to 'recreational' forms of cannabis that are taken for the high associated with the drug.

For epilepsy, much of the debate centres around cannabidiol (CBD), a non-psychoactive component of the cannabis plant that is often sold in 'oil' format. A pharmaceutical-grade CBD medication called Epidiolex has also been developed. Medicinal cannabis can also be used to describe substances that contain both CBD and tetrahydrocannabinol (THC), the component that causes the high.

Does medicinal cannabis work in epilepsy?

This is a complex question that depends on what exactly is meant by 'medicinal cannabis'.

In recent years, a series of clinical trials on a CBD treatment called Epidiolex have shown promising results in reducing seizures in children with rare and severe epilepsies such as Dravet syndrome and Lennox-Gastaut syndrome (link 1; link 2; link 3).

In June 2018, Epidiolex received approval from the US FDA for use in these epilepsies. The drug is currently being reviewed in Europe by the European Medicines Agency and is expected to be approved later in 2018 or early 2019.

However, no other form of CBD or CBD+THC has been proven to be effective in high quality clinical trials.

Anecdotal evidence suggests that treatment with CBD-only products/oils may reduce seizures in some individual patients. However, as with any potential treatment, anecdotal evidence is never sufficient to establish whether or not a treatment has a proven efficacy and safety that would justify its widespread use. The approval of Epidiolex in the US does not mean that other unapproved formulations of CBD oils and products can also be assumed to be effective. The strength of these products can vary from batch to batch and some products purporting to be CBD have been found to contain no CBD at all.

There have also been positive anecdotal reports about products containing both THC and CBD but again, there is currently very little scientific evidence to support these claims.

A report by the Health Protection Regulatory Authority (HPRA) in February 2017 found a lack of scientific data to demonstrate the robust effectiveness of any form of medicinal cannabis. It stated that there was "At best, a moderate benefit for cannabis in a small number of conditions and conflicting evidence, or no evidence at all, in a large number of other medical conditions. The effectiveness and safety of cannabis in large numbers of medical conditions is simply not proven." In addition, "The HPRA considers that there is not currently evidence that cannabinoids are an effective treatment in epilepsy".

In the UK, an All Party Parliamentary Group report by Professor Michael Barnes of Newcastle University found that there is a reasonable evidence base for cannabinoids in the management of chronic pain, spasticity and nausea/vomiting in the context of chemotherapy. However, his detailed report also concluded that cannabis has limited effectiveness in relation to epilepsy.

"Whilst there is a theoretical basis and animal model studies and early human studies are promising, at the moment robust trials are lacking but further results are awaited. There is only limited evidence at the moment", he said.

While recent studies involving Epidiolex have since added to the evidence base, it is important to note that the comments above are still applicable to all other formulations of medical cannabis.

Are there side-effects?

All medicines can potentially have side effects and a significant amount of caution is needed regardless of the drug. Medical supervision is also essential and you should always talk to your medical team before making any changes to your epilepsy medication. If you are taking any form of medicinal cannabis, it is also very important that you tell your doctor as CBD has been shown to interact with certain anti-epileptic drugs (AEDs) and your doctor may need to adjust your AED dosage accordingly.

In relation to side-effects, the 2017 HPRA report stated that "the medical treatment of children and adolescents with cannabis requires careful consideration due to the potential impact on the developing brain. In addition, there is compelling evidence linking cannabis use in adolescence with the development of psychosis in later life."

There are particular concerns regarding the long term effect of THC on mental health and some studies have also shown that THC may be pro-convulsant in some cases (i.e. it makes seizures worse).

Non-approved CBD products are not required to list side effects, but the clinical trials conducted on Epidiolex identified a number of common side effects, which generally were regarded as mild or moderate. These included sleepiness, sedation and lethargy; elevated liver enzymes; decreased appetite; diarrhea; rash; fatigue, malaise and weakness; insomnia, sleep disorder and poor quality sleep; and infections. For more, see the drugs.com page on Epidiolex

Are any cannabis-based treatments already legal?

If a substance contains THC (the psychoactive element), then it is illegal under the Misuse of Drugs Acts. The exception to this is Sativex, a licenced medication that is used to treat spasticity in Multiple Sclerosis. A cannabis-based product that does not contain THC is legal in Ireland. Therefore, CBD oils and products such as Charlotte's Web are available in Ireland, marketed as food supplements. For any of these products, no scientific efficacy or safety data exists, and in many cases, there are significant concerns over the composition and quality control of the products.

Is there any licenced cannabis-based medication available for epilepsy?

A UK company, GW Pharmaceuticals are the leaders in the pharmaceutical application of cannabis. Their drug Sativex has been licenced for treating spasticity in MS. Sativex contains THC and needed a statutory instrument to be exempt from the Misuse of Drugs act. HSE have yet to agree a price with GW, so the drug is still not reimbursed in Ireland. Sativex is not considered to have any therapeutic use in treating epilepsy.

As outlined above, GW has also developed a drug called Epidiolex which was granted FDA approval in the US in June 2018 for use in Lennox-Gastaut syndrome and Dravet syndrome, in patients two years of age and older.

The drug is currently being reviewed in Europe by the European Medicines Agency and is expected to be approved later in 2018 or early 2019.

What is the status of the Compassionate Access Programme?

The 2017 HPRA report was clear that any decision to permit access to cannabis for medical use would be a societal and policy decision rather than a scientific one. It recommended that if treatment with cannabis is permitted it should be under tight control and in limited circumstances. Three conditions were highlighted including "Severe, refractory (treatment-resistant) epilepsy that has failed to respond to standard anticonvulsant medications whilst under expert medical supervision".

Following this, the Minister established an Expert Reference Group to recommend guidelines on how an access programme could be established; in what circumstances medicinal cannabis could be supplied and what form this might take. The group produced draft clinical guidelines in 2017 but as of June 2018, the Scheme has not been made operational.

In May 2018, Minister Harris informed the Cabinet that the department is looking at how best to source medical cannabis products so as to ensure there is an appropriate "quality assurance to help ensure they are safe for use by Irish patients and are affordable". He also stated that the clinical guidelines would be published shortly, that the HSE is preparing a register to facilitate the programme and that the drafting of secondary legislation to underpin the access programme is underway.

Epilepsy Ireland has contributed feedback on the draft guidelines. We understand that in the case of epilepsy, the Scheme will focus on CBD-only products and we support the need to make approved medicines (i.e. Epidiolex) available under the Scheme.

The recent approval of Epidiolex provides a reminder that properly studied, standardised cannabis-based treatments can have a significant impact on improving the quality of life of people currently living with uncontrolled seizures and we urge the Minister to make the long-promised Access scheme operational as soon as possible.

Can the Minister for Health authorise a cannabis product?

It is currently within the Minister for Health's powers to issue a licence for a THC-containing product that would otherwise be illegal.

To date, a number of licences have been applied for and approved by the Minister (see link and link). However, an application cannot be approved by the Minister without the explicit support of a specialist, who must make the application. The Minister does not have any other powers to intervene in the doctor-patient relationship. 

Chronic Pain Ireland have developed a template application which may be used to draft a licence application.

What is the status of the proposed Medicinal Cannabis legislation?

Gino Kenny TD introduced the Medicinal Cannabis Bill to the Dail in 2016 and it has in principle received cross-party support when debated in the Dail. However, the Bill has also been debated at committee stage where significant opposition was expressed and as of June 2018, it is widely acknowledged that significant changes are required in order to make the legislation workable. In July 2017, the Oireachtas Health Committee recommended that the Bill should not proceed back to committee stage, highlighting significant legal issues and the fact that proposed framework was "too loose to effectively guard against leakage of supply to recreational users, [AND] overuse by patients". See Irish Times article. However, in November, the Dail voted to allow the Bill proceed to Committee stage in order to address the issued identified with it.

The future of the Bill remains unclear due to numerous concerns including references to recreational use, the proposed role of medical professionals, the setting up of two new 'quangos' and the separation or medicinal cannabis regulation from the regulation of all other medicines.

How does it work in other countries?

Medicinal cannabis laws have been introduced in a number of countries. In the EU, this includes Netherlands, Italy and Czech Republic. Other programmes exist in Canada, Israel, Australia and in many US states. Other countries, including in the EU have programmes for 'exceptional use' or are in the process of revising laws. There is no uniform system and access programmes differ substantially across the world. There is more on this in the HPRA Report. The UK situation is very similar to Ireland and in June 2018, a review of the legal position of medical cannabis was announced by the UK Government.

What is the Medical Profession's stance on medicinal cannabis?

The National Epilepsy Clinical Care Programme (NECCP) has issued a statement in 2017 highlighting the lack of scientific evidence for all cannabis products other than Epidiolex. They state: "No other cannabis derivatives or products have been adequately studied to a level that they are proven to be effective and safe to use in clinical practice. Specifically, products containing THC remain inadequately tested."

What is Epilepsy Ireland's position on medicinal cannabis?

Given the devastating impact of rare epilepsies like Dravet Syndrome and the limited success of existing drugs in treating these conditions, it is understandable that many affected families are reaching out for the potential benefits provided by medical cannabis. 

Epilepsy Ireland has long held an evidence-based position on medical cannabis and we agree with the path recommended by the HPRA in 2017. We also fully support the position of the NECCP and with the need for further research on all aspects of medicinal cannabis.

Our current position (which may evolve as more evidence becomes available) can be summarised as follows:

  • As an organisation that funds epilepsy research, Epilepsy Ireland welcomes all research that seeks to develop safe and effective treatments for epilepsy including trials on cannabis-based products that may lead to approved medical treatments.
  • We welcome the recent approval of Epidiolex in the US following a series of robust clinical trials (link 1; link 2; link 3). We hope that it will shortly be approved for use in Europe in the near future and we will advocate for access to the drug in Ireland once approved, and in the interim, via the proposed Access Scheme.
  • We support the proposed Access Scheme as a safe, regulated pathway to enabling access to proven cannabis-based medicines to people who could potentially benefit from them.
  •  A clear distinction needs to be drawn between approved medications such as Epidiolex that have undergone rigorous efficacy and safety testing and non-pharmaceutical products (whether CBD or CBD+THC) that are not licenced for medicinal use. There are serious concerns about the safety and risks associated with unregulated, un-standardised non-pharmaceutical products containing cannabis extracts, in particular those that contain THC.
  • While there have been positive anecdotal accounts of some of these products, no robust evidence from high quality scientific studies exists to support the use of non-pharmaceutical cannabis-based products for the treatment of epilepsy. Individual successful cases do not provide strong enough evidence to expose large amounts of people to the unknown and unquantifiable risks associated with unregulated, un-standardised products. In the absence of robust evidence, these products cannot currently be considered as safe or effective treatments for epilepsy.
  • As with any potential treatment, further research, in the form of well-regulated clinical trials represent the only safe and objective way to assess the potential of cannabis based products in the mainstream treatment of epilepsy. Epilepsy Ireland has invited applications under our Research Funding Scheme from researchers who want to pursue this area of research.
  • We do not have a position on the legal status of cannabis for recreational or non-medical purposes.

More Information

Attached Documents

PDF icon HPRA Report on Medicinal Cannabis (HPRA_Report_on_medicinal_cannabis.pdf | 1.01 MB)
PDF icon The Barnes Report (UK) (Barnes_Report.pdf | 798 kB)
PDF icon Cannabis for Medicinal Use Bill (b7616d.pdf | 491 kB)

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