The U.S. Food and Drug Administration has issued a warning on Amgen Inc.'s anemia drugs Aransep and Epogen, saying they could cause a blood condition known as aplasia, according to media reports. Federal regulators also named New Brunswick, N.J.-based Johnson & Johnson’s anemia drug Procrit in the warning and advised physicians to discontinue use of the tratment in patients who develop symptoms of the condition, which can damage red blood cells.