Pharmacokinetic Study of Ferumoxytol: A New Iron Replacement Therapy in Normal Subjects and Hemodialysis Patients

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Abstract
Currently available intravenous iron preparations are not ideal, either because of safety concerns or dose limitations. We investigated the safety and pharmacokinetics of ferumoxytol, a new iron replacement therapy, in normal subjects and hemodialysis patients. In a randomized, double-blind, ascending-dose study in normal volunteers (n = 41), 6 subjects received placebo, and 8 subjects each received ferumoxytol, at 1, 2 or 4 mg iron/kg, injected at 60 mg iron/min. The remaining subjects received 4 mg iron/kg at injection rates of 90 (n = 3), 180 (n = 3) or 1,800 mg iron/min (n = 5). In the second, open-label, ascending-dose study, 20 hemodialysis patients received 125 or 250 mg of iron over 5 min. In normal subjects, the blood half-life of ferumoxytol increased with increasing dose from 9.3 to 14.5 h (p < 0.05) but not with increasing rate of injection. The drug half-life in hemodialysis patients was similar to normal subjects. Ferumoxytol was not removed with hemodialysis. Serum iron (p < 0.001), transferrin saturation (p < 0.001) and ferritin increased in both populations. No serious adverse events were attributable to ferumoxytol. Ferumoxytol was well tolerated in this study. Its pharmacokinetic properties and simplicity of administration suggest that it will be an attractive form of iron replacement therapy.