Management at Baxter Healthcare in Co Mayo has written to workers following the recent announcement of global restructuring by the US multinational.
The company is to introduce "a series of strategic actions to drive the company's operational effectiveness and improved long-term performance".
Baxter International plans to spin off its renal care and acute therapies units into a separate company.
It is also exploring alternatives for BioPharma Solutions which is Baxter's contract manufacturing business.
The manufacturing facility at Castlebar currently employs in the region of 700 people.
In a letter to workers, a company spokesperson said that while it was still early days following the announcement, the Castlebar and Swinford operation is approximately 70% renal and will be directly impacted by the change.
He said the time frame for these changes would take approximately 18-24 months to complete and staff will be kept informed on progress by the local management team.
Manufacturing Division Organiser at SIPTU Greg Ennis said that while there are no imminent changes being proposed at the Castlebar plant, the union will be meeting with management shortly to discuss these latest developments and to get an update on strategic changes.
The company has told staff that a significant part of the work ahead will be to finalise a plan to separate manufacturing, where possible, and establish Transitional Service Agreements for locations that cannot be dedicated to one business or the other.
The company says it will provide more information about the separation plan and roadmap later in the process.
Baxter says that as of now, all employees' terms and conditions remain unchanged.
The company says that the restructuring will create a new simplified operating model for Baxter to help streamline its commercial and manufacturing footprint.