Alkermes plc has announced a definitive agreement to acquire Avadel Pharmaceuticals plc, a commercial-stage biopharmaceutical company, in a transaction valued at approximately $2.1 billion.

Under the terms of the agreement, Alkermes will pay up to $20.00 per share in cash, including a contingent value right (CVR) of $1.50 per share tied to regulatory milestones. The acquisition price represents a 38% premium to Avadel’s three-month volume-weighted average share price and a 12% premium to its closing price on October 21, 2025.

The transaction has received approval from the boards of directors of both companies and is expected to close in Q1 2026, pending regulatory and shareholder approvals.

The acquisition will add Avadel’s lead product, LUMRYZ (sodium oxybate)—a once-at-bedtime treatment for cataplexy or excessive daytime sleepiness in narcolepsy patients aged seven and older—to Alkermes’ commercial portfolio. LUMRYZ received FDA approval in 2023 and has shown strong market uptake, with approximately 3,100 patients on therapy as of mid-2025. Avadel projects 2025 net revenues of $265–$275 million, with continued growth potential in a U.S. narcolepsy market estimated to include over 50,000 oxybate-eligible patients.

Alkermes stated that the acquisition will accelerate its entry into the sleep medicine market and complement its late-stage development pipeline, including alixorexton, an orexin 2 receptor agonist currently advancing toward Phase 3 trials for narcolepsy. The company also cited strategic synergies with Avadel’s commercial infrastructure and rare disease expertise.

The CVR component of the deal is contingent on final FDA approval of LUMRYZ for idiopathic hypersomnia by the end of 2028. Avadel is currently conducting a Phase 3 trial in this indication.

Alkermes also plans to leverage the combined organization’s resources to advance additional orexin receptor agonists in its pipeline, including ALKS 4510 and ALKS 7290, both in Phase 1 development.

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