Pfizer is axeing 150 jobs at one of its plants in Ireland.
The company said the redundancies at its operation in Newbridge, Co Kildare, are a result of increased competition.
In 2010, the drug manufacturer announced it was making 275 workers redundant at the same site.
It is understood most of these job losses came this year.
Paul Duffy, vice president at Pfizer, said the expiry of patents on key medicines and more generic competition meant the company had to cut back on manufacturing.
“Ireland remains a key strategic location for Pfizer with many of our leading and newest medicines manufactured here and the company continues to make investments in the Irish operations,” he added.
“Obviously this announcement has a significant impact for our colleagues. We will provide them with support to help prepare for the challenges ahead.”
The Newbridge plant makes three billion tablets and 55 million packs of medication every year.
Opened in 1992, it is a major employer in the town and employs around 670 people.
Mr Duffy said the Newbridge site remains a key operation for Pfizer.
The pharmaceutical company employs more than 3,200 people at a number of plants in Ireland, including Grange Castle in Dublin and Ringaskiddy in Co Cork.
Representatives of trade union Siptu will meet Pfizer management on Friday.
Organiser Frank Jones, who represents about 70 workers, said the cuts are deeply distressing to workers and their families and will have a devastating effect on the Newbridge area.
“The timing and phasing of these job losses is particularly of concern,” he said.
“We believe that the pool of workers who will accept a voluntary redundancy package has been exhausted.”