Cannabidiol effective in treatment of severe childhood epilepsy - study

The University of Otago trial involved 120 children or young adults.

Cannabidiol has shown to be effective for a severe form of epilepsy, according to a new University of Otago study.

The study, published in the New England Journal of Medicine, is the first Class 1 clinical trial of the drug cannabidiol and has shown it is effective at reducing convulsive seizures in Dravet syndrome - a severe childhood epilepsy disorder associated with drug-resistant seizures, developmental delay, and a high mortality rate.

The only New Zealander on the project was Associate Professor Lynette Sadleir, an epilepsy researcher and paediatric neurologist at the University of Otago in Wellington.

Associate Professor Lynette Sadleir. Photo / supplied

"This study is significant because it is the first scientific clinical evidence we have of an effect of a plant-derived cannabinoid therapeutic medication on epilepsy," she said.

"Previous reports of effects, widely reported in the media, were of individual children and it was unclear if these reflected a true effect for children in general with this type of epilepsy."

Associate Professor Sadleir's expertise is in diagnosing children with specific types of epilepsy.

She was part of an international team whose role was to confirm for the trial that the children included in the study did indeed have Dravet Syndrome.

"Seizures are difficult to control in the Dravet Syndrome," she said.

"It is a rare genetic form of epilepsy that we have been doing a lot of research on.

"This syndrome is a result primarily of loss-of-function of a sodium channel in the brain caused by mutations of a specific gene, called SCN1A."

She said the trial was multinational and placebo-controlled and involved 120 children and young adults with the Dravet syndrome and drug-resistant seizures.

They received either cannabidiol oral solution or placebo, in addition to standard anti-epileptic treatment.

"We found that convulsive seizures in children on the cannabidiol decreased from 12 to six seizures per month, while those children taking placebo only decreased from 15 to 14 seizures per month," she said.

"In addition, 5 per cent of children became seizure free on cannabidiol, while no child became seizure free on placebo.

"The children taking cannabidiol did however have more reported side effects than those on placebo, including diarrhoea, vomiting, fatigue, fever, sleepiness and abnormal liver function.

"These were so significant that 13 per cent of the children taking cannabidiol withdrew from the study due to side effects."

Sadleir said it was important to remember that the medication used in this trial was a 97 per cent pure cannabidiol pharmaceutical grade medication.

"And the results cannot be extrapolated to non-pharmaceutical grade products," she said.

"Also, this was a brief trial lasting only three months so we do not know what the long term effects of this medication on a child's developing brain might be.

"More research is needed but this trial is a positive beginning to our understanding of how cannabidiol may help children with this severe epilepsy."