Iron indices and intravenous ferumoxytol: time to steady-state

The ongoing nature of iron loss in patients receiving hemodialysis makes it difficult to maintain adequate iron stores without supplementation. The effects of ferumoxytol on iron indices have been measured 35 days after baseline, but no study has assessed indices at earlier points in time.

To evaluate the time to transferrin saturation (TSAT) and ferritin stabilization, the point at which TSAT and serum ferritin levels can be accurately measured during a 13-treatment period following a loading dose of ferumoxytol.

Ferumoxytol was administered according to the package insert to 15 adults undergoing hemodialysis. Vital signs were recorded before treatment, 30 and 60 minutes after receiving ferumoxytol, and at the end of treatment to monitor for adverse reactions and hemodynamic instability. Monitoring continued for a 13-treatment period (30 days) after drug administration. Blood was collected throughout the study to measure TSAT, ferritin, hemoglobin (Hb), and C-reactive protein (CRP).

TSAT values at 14, 21, and 28 days after drug administration were not significantly different from those at 7 days, signifying that TSAT values stabilized by day 7. Serum ferritin values at day 14 were significantly lower than those 7 days after drug administration (p = 0.028). Although serum ferritin values at days 21 and 28 tended to decrease relative to values at day 14, the differences were not statistically significant. Therefore, it appears that serum ferritin stabilized by day 14 after drug administration. Mean (SD) Hb values at screening and at end of the study were 11.7 (1.0) g/dL and 12.0 (0.9) g/dL, respectively (p = NS). CRP also did not change significantly throughout the study period.

Dialysis patients achieve stable iron indices quickly. TSAT stabilized by day 7 and ferritin stabilized 14 days after a loading dose of ferumoxytol 1 g. Adverse effects were minimal and did not necessitate discontinuation of ferumoxytol.