Iron-Based Phosphate Binder Safely Treats Anemia in CKD Patients

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In a study 52.1% of patients receiving ferric citrate attained a 1.0 g/dL or greater increase in hemoglobin compared with just 19.1% receiving placebo.
In a study 52.1% of patients receiving ferric citrate attained a 1.0 g/dL or greater increase in hemoglobin compared with just 19.1% receiving placebo.

The oral iron formulation ferric citrate, which is FDA approved as a phosphate binder for dialysis patients, may be a viable alternative to intravenous iron for treating iron-deficiency anemia in patients with non-dialysis dependent chronic kidney disease (NDD-CKD), according to a new study.

Ferric citrate treatment partially corrected anemia in patients with low hemoglobin (9.0–11.5 g/dL), ferritin stores of 200 ng/mL or less, and transferrin saturation at or below 25%. Patients had been unresponsive or intolerant to other oral iron supplements.

In a double-blind phase 3 trial of 232 patients NDD-CKD patients (117 and 115 randomly assigned to receive ferric citrate and placebo, respectively), Glenn Chertow, MD, MPH, of Stanford University School of Medicine and colleagues, found that 52.1% of ferric citrate users achieved a 1.0 g/dL or greater increase in hemoglobin at any time point during the 16-week trial compared with just 19.1% of placebo recipients, according to a paper published online ahead of print in the Journal of the American Society of Nephrology. The mean change in hemoglobin was 0.84 g/dL for ferric citrate users. A response to the oral drug, which contains 210 mg elemental iron in each 1 g tablet and was titrated from 3 tablets daily, was observed as early as 1–2 weeks. A significantly higher proportion of ferric citrate patients achieved a sustained increase in hemoglobin of at least 0.75 g/dL over a 4-week period: 48.7% vs 14.8%.

The erythropoietic response with ferric citrate was similar with that observed in previous trials of NDD-CKD or dialysis patients, the investigators noted. In the current trial, none of the patients received intravenous iron, erythropoietin-stimulating agents (ESAs), or blood transfusion.

“With the high prevalence of iron deficiency anemia in patients with CKD and the risks and inconvenience of alternative therapies, oral ferric citrate may broaden therapeutic options for iron deficiency anemia in this population,” Dr Chertow and colleagues wrote.

Trial participants had serum phosphate levels of 3.5 mg/dL and above. Over the 16-week trial, ferric citrate reduced serum phosphate by 0.21 mg/dL. It also reduced levels of parathyroid hormone and c-terminal and intact fibroblast growth factor-23.

The most common adverse effects with ferric citrate were diarrhea and constipation. Serious adverse events were reported by 12% of ferric citrate and 11.2% of placebo patients.

Since the trial focused on laboratory outcomes, future research is needed to see whether the drug achieves hard endpoints, such as improved survival or better quality of life.

The study was funded by Keryx Biopharmaceuticals, the makers of Auryxia (ferric citrate). Several study authors are employees of the company.

References

  1. Fishbane S, Block GA, Loram L, Neylan J, Pergola PE, Uhlig K, and Chertow GM. Effects of Ferric Citrate in Patients with Nondialysis-Dependent CKD and Iron Deficiency Anemia. J Am Soc Neph. January 12, 2017, doi:10.1681/ASN.2016101053. [Epub ahead of print].
  2. Trial Finds Oral Iron Drug Safe and Effective for Treating Anemia in Kidney Disease Patients. American Society of Nephrology. January 12, 2017 [press release].
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