Efficacy of oral iron therapy in patients receiving recombinant human erythropoietin

Abstract

Iron supplementation is required by most dialysis patients receiving recombinant human erythropoietin. The efficacy of oral iron is variable in these patients, and many require the use of intravenous iron dextran to maintain adequate iron levels, defined as transferrin saturation greater than 20%, serum ferritin greater than 100 ng/mL, and serum iron greater than 80 μg/dL. To determine the efficacy of different oral iron preparations in maintenance of iron status, we prospectively studied 46 recombinant human erythropoietin-treated patients and randomized them to receive different oral iron preparations. These four preparations included Chromagen (ferrous fumarate; Savage Laboratories, Melville, NY), Feosol (ferrous sulfate; SmithKline Beecham, Inc, Pittsburgh, PA), Niferex (polysaccharide; Central Pharmaceuticals, Inc, Seymour, IN), or Tabron (ferrous fumarate; Parke-Davis, Morris Plains, NJ). All patients were prescribed approximately 200 mg of elemental iron daily of their assigned iron preparation with at least 100 mg ascorbic acid daily for 6 months. At baseline and bimonthly during the study, serum iron, transferrin saturation, ferritin, hematocrit, and recombinant human erythropoietin dose were monitored; in addition, compliance and side effects were recorded by patient interview. All patients were able to maintain target hematocrit during the 6 months of study. However, there were differences in the trends of serum iron, percent transferrin saturation, and ferritin when considered singly or in combination between the four groups of iron medications. The percent of laboratory values measured over the study period in each group that met the criteria of transferrin saturation more than 20% was greatest in the Tabron group (58%), followed by the Feosol (47%), Chromagen (33%), and Niferex (31%) groups. For the combined criteria of transferrin saturation greater than 20%, iron greater than 80 μg/dL, and ferritin greater than 100 ng/mL, the largest percent of values meeting this criteria was in the Tabron group (16%), followed by the Chromagen (7%), Feosol (6%), and Niferex (3%) groups. However, because of the small number of patients in each group, these differences were not statistically significant. Incidence of side effects was low in all groups, and there were no major differences in compliance. We conclude that with emphasis on compliance, oral iron supplementation at the dose used for this study can maintain adequate iron status in the short term without the need for iron dextran; however, the downward trend in ferritin in three drug groups indicates that intravenous iron dextran eventually may be necessary for some of these patients.