Concerns over Johnson & Johnson's anti-anemia drug, Eprex, were renewed this week after a report in the New England Journal of Medicine confirmed that the medication is linked to a recent increase in pure red cell aplasia (PRCA) cases. PRCA is a condition characterized by a near absence of red blood cell precursors. Seventy-five cases of Eprex-related aplasia have been reported in Europe and Canada. J&J remains perplexed as to the cause of the disorder.

Eprex is a man-made version of human erythropoietin (EPO). EPO is produced naturally in the body, mostly by the kidneys. It stimulates the bone marrow to produce red blood cells. If the body does not produce enough EPO, anemia can occur. This often occurs in people whose kidneys do not function properly. Johnson & Johnson maintains that Eprex sales should exceed $1 billion this year despite the warning. PRCA is estimated to affect less than one in 10,000 people.