2017 | United States and Europe | Randomized placebo-controlled trial
Devinsky O et al. New England Journal of Medicine. 2017;376:2011-2020.
Methods: Investigators randomized 120 children and young adults with drug-resistant Dravet syndrome to purified oral CBD or placebo, alongside existing antiseizure medicines. The primary comparison covered 14 weeks.
Findings: Median monthly convulsive seizure counts fell from 12.4 to 5.9 with CBD, compared with 14.9 to 14.1 with placebo. CBD produced a greater reduction in the primary seizure outcome, with more adverse events.
Limitations: The study involved a specific epilepsy syndrome and a standardized pharmaceutical preparation. It does not establish equivalent effects for dispensary CBD, other epilepsy types, or replacement of existing medicines. Longer-term outcomes require separate evidence.