Amgen has confirmed that it intends to spend $1 billion in expanding its manufacturing facilities in Puerto Rico, just days after committing the same amount to an expansion programme in Ireland.

The company said that the investment programme in its manufacturing capacity was required to help it meet rising demand for its products around the world, particularly its long-acting biologics Neulasta (pegfilgrastim) and Aranesp (darbepoetin alfa).

A plant currently making Neulasta and its short-acting cousin Neupogen (filgrastim) is being enlarged and will be joined by a new facility making Aranesp and related product Epogen (epoetin alfa), said Amgen. A new formulation, fill and finish facility will also be built at the site in Juncos.

Overall, the programme will add approximately 500 staff members in Puerto Rico by 2010.

Last week Amgen announced plans to invest approximately $1 billion in new bulk protein manufacturing and formulation, fill and finish facilities in Cork, Ireland, that will give the company capacity closer to the patients it serves in Europe.

It also said that it intends to expand its existing research and development operations in the UK and USA.

Amgen maintains that this huge investment programme is also needed to deliver its pipeline to patients, a view backed up by a recent report by Datamonitor, which said the company was likely to be the only one among the top 20 biotech/pharmaceutical majors to post double-digit growth between 2005 and 2011, helped by strong in-house R&D and a canny licensing strategy.