“Dravet syndrome (severe myoclonic epilepsy of infancy) is characterised by difficult-to-control seizures. Media reports and small clinical trials suggest that cannabidiol, a non-toxic extract of cannabis, can reduce seizure frequency. A recent multicentre randomised controlled trial of 120 children aged 2–18 years with Dravet syndrome supports its efficacy.

Over a 14-week period, children taking 20 mg/kg/day of cannabidiol had a 22.8% reduction (95% confidence interval 5.4–41.1) in seizure frequency compared to a 4-week baseline period. Median convulsive frequency fell from 12.4 to 5.9 per month on cannabidiol, while the placebo group had no change from baseline. No attempt was made to measure non-convulsive seizures (e.g. absences). Subjects took a median of three other anti-convulsant drugs during the trial. Adverse effects were common with cannabidiol, particularly somnolence, fatigue, loss of appetite, vomiting and diarrhoea. Eight patients in the cannabidiol group withdrew compared to one in the placebo group.

Nevertheless, 62% of caregivers in the cannabidiol group felt the patient’s overall condition had improved, using a validated global score, compared to 34% in the placebo group (P = 0.02). Unfortunately, the high rate of adverse events may have led to widespread loss of caregiver blinding, and the study is relatively short term. Nevertheless, the reduction in seizures is clinically relevant, and further longer-term randomised controlled trials are clearly warranted. ” https://www.ncbi.nlm.nih.gov/pubmed/29314377  http://onlinelibrary.wiley.com/doi/10.1111/jpc.13803/full