Annual Cost for Stiripentol (Diacomit)
Stiripentol, approved for Dravet syndrome in patients 2+ years old taking clobazam, costs about $95,000 per year at standard dosing (50 mg/kg/day for a 20 kg child). Prices vary by weight and pharmacy; wholesale acquisition cost (WAC) is roughly $3,170 per 500 mg capsule.[1]
Annual Cost for Fenfluramine (Fintepla)
Fenfluramine, also for Dravet syndrome (and Lennox-Gastaut) in patients 2+ years old, runs around $85,000-$90,000 annually at typical doses (0.4 mg/kg/day for a 20 kg child). WAC is about $2,830 per 2.34 mg/mL bottle (180 mL).[1]
Direct Cost Comparison
Fenfluramine is typically $5,000-$10,000 cheaper per year than stiripentol for equivalent pediatric patients, a 5-10% savings. Both require prior authorization and have patient assistance programs that can reduce out-of-pocket costs to $0-$5,000/year for eligible insured patients. Uninsured prices exceed $100,000/year for either.[1][2]
Factors Driving Price Differences
Stiripentol's higher cost stems from orphan drug status, limited competition, and higher per-unit pricing despite similar manufacturing. Fenfluramine benefits from recent generic challenges and broader approvals, pressuring pricing. Neither has generic versions available yet—stiripentol's patents expire around 2028, fenfluramine's in 2031-2033.[1][3]
Insurance Coverage and Real-World Costs
Most commercial plans cover both at 80-100% after step therapy, but Medicaid caps stiripentol higher in some states. Patient forums report fenfluramine easier to get approved due to more trial data. Copays average $50-$200/month with assistance.[2][4]
How Costs Compare to Alternatives Like Cannabidiol (Epidiolex)
Epidiolex costs $120,000+ annually, making both stiripentol and fenfluramine cheaper options. Combinations (e.g., fenfluramine + clobazam) often total under stiripentol monotherapy.[1][2]
[1]: DrugPatentWatch.com (WAC and patent data for Diacomit and Fintepla).
[2]: GoodRx pricing aggregates, 2023-2024.
[3]: FDA Orange Book and patent listings.
[4]: Dravet Syndrome Foundation patient reports.