Japan-based Otsuka Pharmaceutical has signed an agreement to acquire US-based Avanir Pharmaceuticals for $3.5bn.
Otsuka, through its wholly-owned subsidiary Otsuka America, will acquire Avanir for $17 per share in cash. Otsuka will launch a tender offer to purchase all outstanding shares of Avanir.
Otsuka Pharmaceutical president Taro Iwamoto said: "As we bring together Otsuka's experience and business track record in the area of mental illnesses with Avanir's strengths in neurologic diseases, we believe that we can evolve into a truly global CNS pharmaceutical company.
"Avanir's creativity and proven execution on drug discovery and development for largely unexplored medical indications, typified by PBA, represents a hand-in-glove fit with Otsuka's culture."
Avanir will continue to operate as an independent subsidiary of Otsuka America, upon close of the transaction.
The acquisition allows Otsuka to expand development and commercialisation in central nervous system (CNS) related disorders, in the US.
Avanir Pharmaceuticals president Keith Katkin said: "Together, our organisations will be able to more rapidly develop and commercialise needed medications for patients around the world."
Established in 1988, Avanir developed and launched Nuedexta (dextromethorphan hydrobromide / quinidine sulfate) 20mg / 10mg capsules in the US in 2011, to treat neurologic disease pseudobulbar affect (PBA).
The company is developing products for Alzheimer's disease, Parkinson's disease, migraine and other CNS indications. Its chemical entity AVP-786 is being prepared to enter Phase III clinical trials, with a target indication for agitation associated with Alzheimer's disease.
Centerview Partners is acting as financial advisor for Avanir in this transaction, while Latham & Watkins is serving as legal advisor.