On June 30, 2009, the United States Food and Drug Administration (FDA) approved ferumoxytol (Feraheme injection, AMAG Pharmaceuticals), an iron-containing product for intravenous (IV) administration, for the treatment of iron deficiency anemia in adult patients with chronic kidney disease (CKD). The safety and efficacy of ferumoxytol were assessed in three randomized, open-label, controlled clinical trials. Two trials evaluated patients with nondialysis dependent CKD and a third trial assessed patients undergoing hemodialysis. Randomization was either to ferumoxytol or oral iron. Ferumoxytol was administered as two 510 mg IV injections, separated by 3-8 days. Oral iron, Ferro-Sequels, was administered at a dose of 100 mg twice daily for 21 days. In all three clinical trials, ferumoxytol administration increased the mean blood hemoglobin (Hgb) concentrations by approximately 1.0 g/dL over the 35 day period, a mean increase that was greater than what was observed in patients receiving oral iron. Patients receiving ferumoxytol also had increases in blood transferrin saturation (TSAT) and ferritin values. For the proposed ferumoxytol dosing regimen, 4.9% of patients had serum ferritin >or=800 ng/mL and TSAT >or=50% post-treatment. The most important ferumoxytol safety concerns were hypersensitivity reactions and/or hypotension. Anaphylaxis or anaphylactoid reactions were reported in 0.2% of subjects, and other adverse reactions potentially associated with hypersensitivity (e.g., pruritus, rash, urticaria, or wheezing) were reported in 3.7%. Hypotension was observed in 1.9%, including three patients with serious hypotensive reactions. Ferumoxytol administration may transiently affect the diagnostic ability of magnetic resonance imaging and the drug label provides further information regarding this effect.