Horizon Therapeutics, PLC is an Irish company based in Dublin. It is the manufacturer and distributor of Tepezza. However, another Irish company, Amgen, Inc., acquired Horizon Therapeutics, PLC in December of 2022, according to Healio News. However, this merger is not yet approved for business in the United States.
If the merger receives approval in the U.S., Amgen may also be liable. Even if Amgen chose to end sales of Tepezza, it could still face liability under the doctrine of successor liability.