Fenfluramine treatment in adults with Dravet syndrome: experience so far from three UK centres

<h3></h3> Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterised by life- long, treatment-resistant seizures. Fenfluramine (FFA) has been shown to be effective for treating seizures in DS. However, almost all published studies of FFA in DS include only children (&lt;18 years), including all three randomised control trials. We conducted a prospective, observational, service evaluation across three UK centres to evaluate the efficacy, tolerability, and safety of FFA for treating seizures in adults with DS. Eleven adults with DS were included: median age 25 years (range 17–32), 55% female, median number of concurrent antiseizure medications (ASM) four (range 2–5). After 6-months of FFA treatment, 7/11 (64%) had a ≥50% reduction in convulsive seizures; 3/11 (27%) became free of convulsive seizures. One individual stopped FFA due to lack of efficacy, and one due to side effects. Drowsiness/tiredness was reported by 8/11 (73%) and necessitated ASM changes in 5/11 (45%). Three individuals have been treated for 12 months; all maintained a ≥50% reduction in convulsive seizures. No individuals developed cardiac valvulopathy. FFA is effective for the treatment of seizures in adults with DS, resulting in convulsive seizure freedom in some. Drowsiness/tiredness is a common side effect of FFA in adults, often necessitating ASM changes.