Trial confirms antiepileptic effects of fenfluramine in children with Dravet syndrome

Children with Dravet syndrome, a severe form of epilepsy that is resistant to treatment, experience fewer seizures when treated with fenfluramine, a phase III trial published in The Lancet (17 December 2019) has confirmed^[1]
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The study also provides reassurance around fenfluramine’s heart-related side effects, which led to the drug’s withdrawal as a weight loss agent in the 1990s.

Researchers randomly assigned 119 children and young adults (mean age nine years) with Dravet syndrome, who had an average of 40 seizures every 28 days, to receive placebo, fenfluramine 0.2mg/kg/day or fenfluramine 0.7mg/kg/day, added to existing antiepileptics for 14 weeks.

Seizure frequency was reduced on average by 74.9% in the high-dose fenfluramine group, by 42.3% in the low-dose group and by 19.2% in the placebo group.

The researchers estimated that, compared with placebo, those given the higher dose of fenfluramine experienced a 62% (95% confidence interval 47.7–72.8; P<0.0001) reduction in the mean number of seizures. No heart-related side effects were observed.

“We saw impressive reductions in seizures in the patients who received fenfluramine compared with those on the placebo and, although further study will need to assess the long-term safety, I am optimistic about what we have seen so far,” said Helen Cross, head of the developmental neuroscience programme at UCL Great Ormond Street Institute of Child Health in London and one of the authors of the study.