The use of medical cannabis to treat seizures has been in the news a lot this week due to the current case involving 12-year old Billy Caldwell. Last month, a study was published in the New England Journal of Medicine on the results of a clinical trial of the effects of Cannabidiol on drop seizures in Lennox-Gastaut syndrome.
Lennox-Gastaut syndrome is a rare form of childhood-onset epilepsy that is difficult to treat and is often debilitating. Drop seizures, also known as atonic seizures, are a type of seizure where partial or complete loss of muscle tone occurs for a short period of time – typically less than 15 seconds. They are called drop seizures due to the characteristic drop of the head that occurs from the relaxing of muscles in the neck.
Cannabidiol, also known as CBD, is a compound extracted from the cannabis plant. It does not contain any THC – the psychoactive extract from the cannabis plant that recreational users use to get “high”.
The trial of 225 children and adults with Lennox-Gastaut syndrome, compared cannabidiol to a placebo. The scientists found that adding cannabidiol to the conventional antiepileptic treatment resulted in a greater reduction in drop seizures and other types of seizures than the placebo. However, the cannabidiol group also experienced more side effects than the placebo group, including drowsiness and diarrhoea. The cannabidiol used in this trial did not contain any THC. The results of this trial were similar to those of previous studies investigating cannabidiol in patients with Lennox-Gastaut syndrome and Dravet syndrome. A clinical trial on possible interactions between cannabidiol and the anti-epilepsy medication clobazam is currently underway.
The trial was funded by GW Pharmaceuticals, who are the leading manufacturers of medical cannabis in the UK.
Regarding the recent press coverage of Billy Caldwell and the use of cannabis oil for treatment-resistant epilepsy, Prof Deb Pal, Professor of Paediatric Epilepsy at King’s College London said: “There is now good evidence from clinical trials conducted in the US and Europe that pharmaceutical preparations of cannabidiol are effective against two types of severe childhood epilepsy known as Dravet syndrome and Lennox-Gastaut syndrome. These types of epilepsy are often resistant to conventional antiepileptic drugs. The evidence from these trials has only recently been published and both the FDA in the USA and the EMA in Europe will now consider the evidence in order to grant a licence for the drug to be used in clinical practice. If successful then the drug would become available to prescribe for named patients towards the end of the year or early next year.
“All new medications need to be thoroughly evaluated for reasons of patient safety, effectiveness and economics. This applies just as much to cannabinoids as to any other pharmacologically active product, perhaps more so given the huge publicity surrounding the medical marketing of cannabis-derived products. It’s important to realise that the trial evidence is for pharmaceutically manufactured medicines, not over the counter preparations that may not have been produced to the same standards or with different components. Nor does it necessarily follow that cannabinoids will be safe and effective for other types of epilepsy. Thus we need to follow the usual processes for new drug approval such as NICE appraisal, otherwise we risk patient safety if we respond to every demand on a case-by-case basis.”
Prof Deb Pal was recently awarded a pilot grant by Epilepsy Research UK to investigate the feasibility of a study investigating the use of nicotine patches in the treatment of sleep-related hypermotor epilepsy.