The Food and Drug Administration has approved Pfizer’s application for Retacrit, a biosimilar of Amgen Inc. and Johnson & Johnson’s anemia drug Epogen. The move increases competition for sales of Amgen’s drug, which have taken a hit in recent quarters due to lower prices and decreased demand.

“Amgen will continue to promote the robust clinical data of our erythropoiesis-stimulating agent ... products including (Epogen), with nearly 29 years of experience,” the company said in a statement to the Business Journal. In addition, the Thousand Oaks biotech is promoting the sale of Aranesp, a similar drug that also is used to treat anemia arising from chronic kidney disease or chemotherapy.

Epogen sales were $244 million in the first quarter of 2018, a 10 percent decrease from the same period a year prior. Sales of Aranesp fell 11 percent year over year, declining from $511 million to $454 million.

Biosimilars are so called because they copy an original drug, but since the medicine is produced inside living cells and the second manufacturer doesn’t have access to the original cell culture, it cannot produce an exact duplicate.

Retacrit has been approved in Europe as an Epogen biosimilar since 2008. Amgen previously attempted to slow its release in the U.S. by filing a request for a court order that would have forced Pfizer to disclose more information about Retacrit to gain FDA approval; the motion was denied by the U.S. District Court of Delaware, as was a subsequent appeal in a federal court. Still, Pfizer had to apply three times before Retacrit was greenlit by the FDA, which held off on approving it due to concerns about the plant at which the medication is manufactured.

Amgen shares (AMGN) fell $3.62, or about 2 percent, on Tuesday to close at $172.34 on the Nasdaq.