Safety and effectiveness of stiripentol in patients with Dravet syndrome: A prospective, 3-year, postmarketing surveillance study.

Aim: To conduct a postmarketing surveillance study of patients with Dravet syndrome in Japan to investigate the safety and effectiveness of long-term, real-world, clinical use of stiripentol (STP).

Method: This prospective study was conducted over 156 weeks in all patients with Dravet syndrome who started STP treatment from its launch in Japan in November 2012 until August 2017. Adverse drug reactions (ADRs) were investigated by degree of seriousness. Effectiveness was determined based on a comprehensive assessment by the physician in charge as well as on the percentage change in the number of seizures from the pretreatment period.

Results: In total, 520 patients (266 males, 254 females; mean age [SD] 10 years 6 months [9 years 10 months]; age range 0-50 years) were included in the safety analysis set, and 515 patients in the effectiveness analysis set. ADRs occurred in 69.2%, including somnolence, decreased appetite, dizziness, in order of frequency. Twelve deaths occurred, the rate of which was not higher than the reported rates. No new safety concerns were identified. The rate of overall improvement (marked or moderate) after 156 weeks or at treatment discontinuation was 37.7%. Decreases in the number of all seizure types over the long term were confirmed.

Interpretation: In real-world clinical settings, long-term STP treatment can be safe and effective in patients with Dravet syndrome.