Gerard Laboratories has confirmed it will create an additional 380 jobs in north Dublin by 2010.
The substantial expansion at the Baldoyle Industrial Estate carries an investment price tag of up to €40 million for the company, a subsidiary of the German Merck group.
About half of the new jobs at Baldoyle will be in production areas, with a further quarter in quality control and the remainder in maintenance and administration positions.
Recruitment is expected to commence in 2004 following the construction of an additional 11,000 sq ft building, which will provide extra laboratory space for the manufacturing of 13 new products.
Planning permission has already been granted and building work will commence in the summer.
The Tánaiste, Ms Harney said: "This investment will enable Gerard Laboratories to triple output and become the group's most important generic pharmaceuticals manufacturing site worldwide. Today's announcement continues Ireland's success as a leading location for significant new high quality investment from global pharmaceutical companies.
"This is a much needed boost for north Dublin, particularly following the announcement last week of the closure of the Celestica plant in Swords and it demonstrates that the area remains an attractive location for investment.
"This success has further enhanced Ireland's reputation as a leading location for such new investments and shows that Ireland, despite the ongoing difficult global economic environment, maintains a competitive edge for high quality, higher value and technologically advanced investments from international companies in these sectors," Ms Harney added.
Gerard Laboratories at Baldoyle is the European manufacturing centre for its parent company, Merck Generics. The facility was founded in 1986 and was acquired by Merck in 1995.
Gerard Laboratories specialises in the production of medicines for cardiovascular and gastrointestinal ailments.
The company said it was one of the major suppliers of branded generic pharmaceuticals to the local market demonstrating significant growth in recent years.