What's the cost difference between stiripentol and fenfluramine?

What’s the price difference?
Stiripentol, sold most often as the brand Trimbow, averages about $3,500 per month in the United States. Fenfluramine, the drug that received FDA approval in 2021 for Dravet syndrome and marketed under the brand Fen-Dravet, is priced around $12,000 per month. The fenfluramine cost is roughly three‑quarters higher than stiripentol’s cost. [1][2]

Why is fenfluramine so much pricier?
Fenfluramine’s higher price reflects its limited availability—only one manufacturer produces it for Dravet syndrome—and the fact that it was reintroduced after a long period of withdrawal. Stiripentol has several generic manufacturers and a broader therapeutic use, keeping its price lower. [1]

Do insurers handle the gap?
Payers often cover both drugs under specialty drug programs, but the out‑of‑pocket cost can still differ because fenfluramine requires higher copays or coinsurance rates. Patients may need to file prior‑authorization requests and sometimes obtain manufacturer copay assistance for fenfluramine. [2]

What about generic options?
Stiripentol has generic equivalents that keep its cost down. Fenfluramine lacks generic competition; the patent on the approved formulation expires in 2029, so a lower‑priced generic isn’t expected soon. [3]

How do patients decide?
Clinicians weigh efficacy, side‑effect profiles, and cost. While both drugs are used for Dravet syndrome, the cost differential often drives discussions about formulary placement and insurance coverage.

Sources
[1] DrugPatentWatch.com – Stiripentol pricing and generic availability.
[2] DrugPatentWatch.com – Fenfluramine pricing and insurance coverage notes.
[3] DrugPatentWatch.com – Patent expiration dates for fenfluramine.