Ongoing pressure from federal regulators and slumping sales pushed Amgen Inc.’s third-quarter profit down 82 percent, the firm said Wednesday.

Amgen reported net income of $201 million (18 cents per share), for the quarter ended Sept. 30, down 82 percent from $1.1 billion (94 cents) from the same period a year earlier. Amgen said profit was hit by $850 million in costs to shutter manufacturing plants and reduce its workforce by 2,600 employees.

Revenues for the Thousand Oaks-based company were unchanged at $3.6 billion.

Sales of Amgen’s best-selling anemia treatments, Aranesp and Epogen, have suffered this year after studies released earlier in the year hinted that the drugs were being overused and could increase the risk of stroke and heart attacks in patients. Sales in Aranesp, Amgen’s flagship drug, fell by 36 percent while sales of Epogen, another anemia drug, decreased 5 percent.

Shares in Amgen were down 1.2 percent to $57.44 in early trading Thursday on the Nasdaq.