World first Australian and New Zealand trial of cannabidiol transdermal gel for the most common hard-to-treat epilepsy type in adults

Professor Terry O'Brien has led a trial using transdermal CBD gel
in adults with focal epilepsy. After 6 months of treatment, over half
the patients experienced a 50%+ reduction in seizures. JAMA study

Medicinal cannabis-based treatments are emerging as promising complementary approaches to improving seizure control in patients with difficult to treat epilepsy. In 2018 the US Food and Drug Administration (FDA) approved the use of a prescription cannabidiol medicine for the treatment of two rare epilepsy diseases that cause treatment resistant seizures, Lennox-Gastaut Syndrome and Dravet syndrome, that predominantly affect children. 

Last year the Australian Therapeutic Goods Administration (TGA) and Pharmaceutical Benefits Advisory Committee (PBAC) approved the prescription, and subsidy on the Pharmaceutical Benefits Scheme (PBS), of this treatment for patients with Dravet Syndrome. However, there is currently limited high-level evidence for the effectiveness and safety of cannabidiol treatments, and their availability, for adults with common forms of epilepsy.

A world-first Phase 2A trial, led by Professor Terry O’Brien, Director of the Monash University Department of Neuroscience and Program Director Alfred Brain, and published in the Journal of the American Medical Association (JAMA Open), looked at the safety of transdermal cannabidiol (CBD) gel in adults with focal epilepsy, which is the most common form of epilepsy in adults (affecting 60% of patients), and is treatment-resistant in one third of patients.

Run across 14 epilepsy trial centres in Australia and New Zealand, the study found that the use of CBD oil in skin patches was safe, well tolerated and accepted by patients. Importantly, while the initial double-blind phase of the trial over 12 weeks of 188 patients did not find a significant difference in seizure frequency between the patients randomised to one of the two CBD oil treatment arms compared to those randomised to receive placebo (inactive) gel, there was a reduction in seizures by at least 50% in more than half of the patients by month 6 of the follow-on open label extension trial.

According to Professor O’Brien, this is the first such trial in the world for the efficacy and safety of a medicinal cannabidiol for the treatment of seizure frequency in adults with focal epilepsy.

“This is the first randomised, double blind, placebo-controlled trial of a cannabidiol in this common group of adult patients, whose seizures currently cannot be controlled with currently available treatments,” he said.

“The original 12-week trial did not show any difference in effect of the gel between the experimental and placebo group, though the trial did show the gel was safe. Importantly, the open label extension of the trial to six months showed a seizure reduction of at least 50% in more than half of the experimental group, making it a promising candidate for further larger and longer trials. This trial represents an internationally significant, landmark trial, to build an evidence base to support the availability and use of medicinal cannabis based treatments for adults with common forms of epilepsy.”

See the paper

O'Brien TJ, Berkovic SF, French JA, Messenheimer JA, Sebree TB, Bonn-Miller MO, Gutterman DL; STAR 1/STAR 2 Study Group. Adjunctive Transdermal Cannabidiol for Adults With Focal Epilepsy: A Randomized Clinical Trial. JAMA Netw Open. 2022 Jul 1;5(7):e2220189. doi: 10.1001/jamanetworkopen.2022.20189. PMID: 35802375.