A large clinical trial conducted on a drug derived from cannabis has demonstrated reduction of convulsive seizures experienced by children with a severe form of epilepsy by nearly 50%[1]
. The results, published in the New England Journal of Medicine (online, 25 May 2017), has generated interest from the mainstream media.
The multicentre international trial randomised 120 children and young adults with Dravet syndrome into a double-blind, placebo-controlled trial of treatment with oral cannabidiol or a placebo. The patients all had drug-resistant seizures.
Dravet syndrome is a particularly distressing form of epilepsy that manifests in the first year of life with seizures and encephalopathy. Initially the condition resembles one of febrile convulsions, but children develop prolonged seizures as they grow, show developmental delay, movement and balance problems and sleep disorders. The condition was once termed severe myoclonic epilepsy of infancy. It was described in detail by Charlotte Dravet in 1978. Although there are many mutations in cohorts of these patients, 70–90% of these affect the SCN1A gene that codes for a unit of a sodium ion channel. The condition is probably underdiagnosed.
After a four-week baseline period on their normal therapy, there was a 14-week trial of treatment. It was found that the median frequency of convulsive seizures reduced in those treated with cannabidiol; their overall condition improved on a global assessment scale. Approximately 5% of children became seizure free in the active treatment group; there were no seizure-free cases in the placebo arm. There were some adverse reactions in the cannabidiol group, including diarrhoea, vomiting, fatigue, sleepiness and abnormal liver function tests [1]
.
The potential for development and initiatives in this area is great. In some countries such as Israel, cannabidiol is already approved for use in paediatric epilepsy. Perhaps specialists in Israel could lead on good practice in this field. More trials and more sophisticated prescriptions for this type of botanical product are likely to follow soon.
This is a good example of how carefully interrogating the value of cannabis products in the treatment of epilepsy has provided helpful, robust data that will help deliver a novel set of therapies.
Colin Michie
Paediatrician, London
References
[1] Devinsky O, Cross JH, Laux L et al. Cannabidiol in Dravet Syndrome study group. Trial of cannabidiol for drug-resistant seizures in the Dravet Syndrome. N Engl J Med. 2017;376(21):2011–2020. doi: 10.1056/NEJMoa1611618
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