Global drugmaking giant MSD has bought the Dunboyne Biologics site from rival firm Takeda Pharmaceuticals in a deal that secures 200 jobs at the facility.
Takeda said in January that it was looking for a buyer for the plant, which it had acquired last year as part of its $62bn (€56bn) takeover of Shire,
Terms of the sale were not publicly disclosed. IDA Ireland, which assisted Takeda in marketing the Dunboyne facility, said MSD's purchase provided maximum security to its work force.
MSD - the trading name in Ireland for Merck - already operates five manufacturing and R&D sites here, including a new biologics plant being constructed in Swords.
It employs more than 2,500 workers here.
IDA chief executive Martin Shanahan said MSD "is a substantial and valued employer whose commitment to Ireland is evidenced by the significant capital investment it has made over the years in its different sites here. This acquisition will allow MSD to further develop the site and secure the employment of Takeda's existing staff.
"It is an excellent outcome," he said.
Shire had spent €375m to build the biologics facility on a 50-hectare site outside Dunboyne, but the plant has yet to enter production.
MSD said it intends to use the Dunboyne plant to make clinical trial stocks of new drugs and treatments.
"This facility will further expand our footprint in Ireland and support commercialisation of our existing and future pipeline of biologics products," said Sanat Chattopadhyay, president of MSD's manufacturing division. "The talent of the team in Dunboyne was a determining factor in our decision to acquire this facility."
MSD's country director for Ireland, Ger Brennan, said the Dunboyne site would "complement our full manufacturing footprint" and provide space to expand operations.
Toyko-based Takeda - the biggest drug company in Asia - remains a major player in Ireland's pharmaceuticals industry.
It employs more than 500 people in Ireland, primarily at its Grange Castle campus.
Susan Hynes, the site lead at Dunboyne Biologics, said staff were relieved and excited to be moving to MSD.
"We believe the announcement today demonstrates the confidence that MSD has that the facility, capabilities and culture we have at Dunboyne will thrive in the new organisation and support long-term growth for the company," she said.
According to official data from the Central Statistics Office, out of total of €152.57bn in exports from the State in 2019, medical and pharmaceutical products sales overseas accounted for a third of the total figure, €49.66bn.
The Central Bank says that just one product category, antisera - used in the manufacture of vaccines - has driven 40pc of the growth in exports of chemicals.