Cannabidiol for resistant seizures in Dravet syndrome

Introduction and clinical context

Dravet syndrome is a rare, severe form of refractory epilepsy, with onset in the first year of life, marked by prolonged tonic-clonic seizures, developmental delay and a strong impact on the quality of life of the child and the family. The difficulty of control with conventional antiepileptics motivated the search for new therapeutic options, among them cannabidiol (CBD), the non-psychoactive compound of Cannabis sativa. This trial evaluated precisely CBD as an adjuvant treatment in this hard-to-manage population.

Methodology and findings

The study (Devinsky and colleagues, New England Journal of Medicine, 2017) is a randomized, double-blind, placebo-controlled clinical trial — the gold standard for rigorously measuring a treatment's effect. Cannabidiol significantly reduced the frequency of convulsive seizures compared with placebo. That result was one of the milestones that underpinned the regulatory approval of purified CBD (Epidiolex) for rare epilepsies. As in any therapy, adverse events were recorded, which reinforces the importance of medical follow-up during treatment. The robustness of the design — with randomization and blinding — confers high reliability on the observed results.

Mechanism of action and safety

Cannabidiol acts on the endocannabinoid system and on multiple targets related to neuronal excitability, which helps explain its anticonvulsant effect. Because it is not psychoactive, it has a profile distinct from THC. Safety points of attention include drug interactions — especially with other antiepileptics, such as clobazam — and the need to monitor liver enzymes. The dose should be titrated gradually, under neurological supervision, with monitoring of effects such as drowsiness and gastrointestinal changes. Regular follow-up allows the dose to be adjusted over time and any undesired effects to be identified early, essential care in the pediatric age group, where reducing seizure frequency represents a direct gain in development and quality of life.

Regulation in Brazil (Anvisa)

In Brazil, access to cannabidiol-based products is regulated by Anvisa, through RDC 660/2022 (patient import with prescription) and RDC 1,015/2026 (new manufacturing and import framework). Treatment requires an individualized medical prescription and neurological follow-up. This content is informative and does not replace the assessment of a healthcare professional.