The company, which employs 519 people at the facility in Brinny, said the job losses would be phased out on a voluntary basis over the next three years.
At a meeting with workers this afternoon, management said it hoped the cost-cutting programme would secure the plant's future.
Alan O'Leary, SIPTU Sectoral Organiser, said today's announcement would be difficult for many of the workers at the plant.
Schering-Plough Site Director John Howell also said that a transformation programme, which the company is going through, presented everybody at the plant with an opportunity to secure further investment at the site in the future.
Mr Howell said the cost-reduction programme was designed to secure the future of the plant within the Merck global network.
Last year, Schering-Plough merged with the multinational pharmaceutical company Merck in a deal valued at the time at $41bn.
