The news comes just one week after the Californian company said it will pump $1 billion into new bulk protein manufacturing and formulation, fill and finish facilities in Ireland, obtaining closer capacity to the patients it serves in Europe.
What is more, with regards to its R&D operations, Amgen is doubling its facilities in the UK and expanding its presence in a number of US cities.
Pushing this investment, at a time when many of its competitors are consolidating and reducing workforces, are a plethora of new drugs in the pipeline and increased global sales - in Amgen's Q4 results revenue was up 12 per cent from a year ago to $3.3 billion, driven by higher sales of its drugs for anemia and arthritis.
Products in the firm's clinical trials include osteoarthritis drug Kineret in Phase 2, autoimmune bleeding disorder drug AMG 531 also in Phase 2, bone disease drug Denosumab in Phases 2 and 3, and highly anticipated colon cancer drug Panitumumab in Phase 3, whose great appeal to investors was tested last month with a delay in the publication of its trial data.
"Our need for increasing capacity is the main driver behind this expansion," Amgen spokeswoman Mary Klem told In-Pharmatechnologist.com.
"We have many products in the pipeline we will need to manufacture and the strong sales we have been seeing is also an important factor."
In Puerto Rico, the world's biggest biotechnology company will expand its existing facilities in its manufacturing complex in Juncos and will construct a new formulation, fill and finish facility, creating 500 new jobs by 2010.
There, Amgen will enlarge its bulk protein manufacturing facility, licensed in 2005, for Neupogen and Neulasta, drugs that boost white blood cells to fight infection in chemotherapy patients.
It will also expand on its the newly built bulk plant for Epogen and Aranesp, treatments for anemia in cancer and kidney dialysis patients.
"By significantly increasing capacity in Puerto Rico and elsewhere around the world, Amgen enhances its ability to supply every patient, every time, with our vital medicines," Fabrizio Bonanni, Amgen's senior vice president for manufacturing, said in a statement.
"We also position ourselves to deliver on Amgen's rich and diverse pipeline."
Explaining the reasons behind its investment in Puerto Rico, the company cited the Caribbean island's attractive business climate and strong commitment to developing biotechnology manufacturing capability, as demonstrated by the formation of the Puerto Rico Science and Technology Trust and establishment of biotechnology manufacturing programmes at University of Puerto Rico Mayaguez.
This year's investments continue a trend of expansion for Amgen, with the company opening a plant for its arthritis and psoriasis drug Enbrel in Rhode Island in 2005 and announcing plans to acquire Abgenix, a leading biopharmaceutical company with a large manufacturing plant in Fremont, California.
Over the last five years, Amgen has spent more than $3 billion to enhance its manufacturing capabilities in the US and has added more than 4,000 operations there since 2001.