Glaxosmithkline is to reduce its workforce at Currabinny, Co Cork, by 100, the pharmaceutical firm said today.
The company said that due to falling sales for a number of the products produced at Cork there was "excess capacity at Currabinny, and this situation is not sustainable".
The Currabinny site produces ingredients for a number of drugs, including Tykerb, which is used in the treatment of breast cancer. Some 500 people are employed there.
Finbar Whyte, GSK Currabinny site director, said the redundancies were not a reflection on the performance of the site or the commitment of the employees.
"Unfortunately, due to falling volumes globally of some of our site's products, we have excess capacity at Currabinny, and this situation is not sustainable," he said.
GSK has recently invested in research and development in Ireland and has two collaborations in place with the Institute of Neuroscience in Trinity College and the Alimentary Pharmabiotic Centre in University College Cork.
Fine Gael spokeswoman Deirdre Clune said the news was a "serious blow to Cork which has been cultivating pharmaceutical operations for many years."
"These job losses at GSK are also worrying in the national context given that the pharmaceutical sector is a lynchpin of Irish manufacturing. The traditional manufacturing sector has been haemorrhaging jobs, whereas high-value pharmaceutical companies are regarded as the key to future growth."