LONGMONT — Officials at Amgen Inc. told employees recently that the company will stop manufacturing the bulk substance for its anemia drug Epogen in 12 to 15 months.

The bulk substance – epoetin alfa intermediate – is made at a manufacturing facility on the Longmont campus, said Peggy Kraus, a local spokeswoman. Thousand Oaks, California,-based Amgen (Nasdaq: AMGN) is not yet sure what impact the decision will have on employees, Kraus said.

“Right now, we don’t have the answer, because there are a lot of things that need to be determined,” Kraus said. “We continue to manufacture in Longmont and at our other facility in Boulder.”

Amgen has about 725 employees in its Boulder County facilities. About 478, or two-thirds, of them are based in Longmont, while about 247 work at the LakeCentre campus in Boulder. The company’s manufacturing personnel travel back and forth between the two sites, Kraus said.

None of the employees is being laid off at the current time, Kraus said. Local employees were told of the decision in June, she said.

Other employees who work at the Longmont campus in another building do process development work, quality work and technology and information services support for all Amgen facilities, she said.

At the same time, Amgen’s Boulder plant has manufactured the bulk substance denosumab, which is used to make Prolia and Xgeva. Those drugs can be used to treat post-menopausal women with osteoporosis.

Also made in Boulder is Amgen-386, a drug still under investigation in the treatment for ovarian cancer, Kraus said.