Here we go again. In an article in the New England Journal of Medicine, Food and Drug Administration officials said that they plan to ask a panel of experts to review the use of erythropoiesis-stimulating agents (ESAs) in patients with chronic kidney disease.

ESAs, which stimulate the production of oxygen-carrying hemoglobins, have come under fire over the last few years, and their sales have suffered.

Drug

Company

2009 Sales through Sept.
(in millions)

Year-over-year Increase (Decrease)

Aranesp

Amgen (NASDAQ:AMGN)

$2,004

(17.6%)

Procrit

Johnson & Johnson (NYSE:JNJ)

$1,669

(12.2%)

Source: Company press releases.

The question basically comes down to how high patients' hemoglobin levels needs to get. If the advisory panel decides that patients should only get enough of the drugs to avoid having a transfusion, it would cut down the amount of drug each patient uses.

Any changes will hit Amgen especially hard. Including its other ESA, Epogen, sales of anemia drugs made up 36% of sales so far this year. The company is also facing competition in Europe and potentially back at home from generic drugmakers like Novartis (NYSE:NVS), Teva Pharmaceuticals (NASDAQ:TEVA) and Hospira (NYSE:HSP).

Fortunately Amgen has a plan to deal with the potential for anemic growth. An approval of its drug candidate Prolia in the treatment of osteoporosis looks imminent, after the FDA asked for more information but didn't want additional trials for that indication. A clinical trial testing Prolia in prostate cancer patients with bone metastases is expected to read out this quarter, which would put it on pace to expand into that additional indication in 2011.

Prolia could be just the transfusion that Amgen needs.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Novartis is a Motley Fool Global Gains pick. Johnson & Johnson is a Motley Fool Income Investor recommendation. The Fool has a disclosure policy.