Ferumoxytol Approved to Treat Iron-Deficiency Anemia in Chronic Kidney Disease

Yael Waknine

July 02, 2009

July 2, 2009 ( UPDATED July 6, 2009 )  — On June 30, the US Food and Drug Administration approved ferumoxytol injection (Feraheme, AMAG Pharmaceuticals, Inc) for the treatment of iron-deficiency anemia in adult patients with chronic kidney disease.

Ferumoxytol consists of a superparamagnetic iron oxide coated with a carbohydrate shell that helps to isolate the bioactive iron from plasma components until the complex enters the macrophages of the liver, spleen, and bone marrow. The iron is released from the complex within macrophage vesicles and then either enters the intracellular iron storage pool (eg, ferritin) or is transferred via plasma transferrin to erythroid precursor cells for incorporation into hemoglobin.

The novel product is expected to be available during the second half of July 2009 and will be marketed in 17-mL single-use vials containing 510 mg of elemental iron. An initial 510-mg intravenous injection, delivered at a rate of up to 1 mL/second (30 mg/second), should be followed by a second 510-mg dose given 3 to 8 days later. Additional 510-mg doses may be administered to patients with persistent or recurrent iron-deficiency anemia.

FDA approval of ferumoxytol was based on data from 3 randomized, open-label controlled clinical trials (n = 1726) that also included an uncontrolled, follow-up phase in which patients with persistent anemia could receive 2 additional doses.

Results showed that ferumoxytol yielded significantly greater mean increases in hemoglobin levels from baseline at day 35 compared with oral iron (ferrous fumarate, 200-mg elemental iron/day) in patients with all stages of chronic kidney disease.

"[The drug] offers patients across the continuum of chronic kidney disease, including patients not on dialysis and patients on dialysis, a new paradigm for the treatment of iron deficiency anemia," commented Brian J.G. Pereira, MD, president and chief executive officer of AMAG Pharmaceuticals, in a company news release.

Ferumoxytol does not cause most of the adverse events associated with oral iron replacement therapies. In clinical trials, the most common adverse reactions (incidence ≥ 2%) reported more frequently with ferumoxytol injection vs ferrous fumarate tablets included hypotension (2.5% vs 0.4%) and dizziness (2.6% vs 1.8%). Events reported with decreased frequency included diarrhea (4.0% vs iron tablets, 8.2%), nausea (3.1% vs 7.5%), constipation (2.1% vs 5.7%), and peripheral edema (2.0% vs 3.2%).

Because of the potential for hypersensitivity reactions and hypotension, patients should be observed for at least 30 minutes after each dose. To avoid iron overload and the potential for iatrogenic hemosiderosis, patients should be regularly monitored for hematologic response, with the caveat that laboratory assays performed in the first 24 hours may overestimate serum iron and transferrin-bound iron by also measuring the iron in the ferumoxytol complex.

As a superparamagnetic iron oxide, ferumoxytol can alter magnetic resonance imaging studies for up to 3 months after the last dose. X-ray, computed tomography, positron emission tomography, single-photon emission computed tomography, ultrasound, and nuclear imaging are not affected.

According to the news release, the company will fulfill requirements of the Pediatric Research Equity Act by conducting 2 postmarketing studies of ferumoxytol in pediatric patients with chronic kidney disease both requiring and not requiring dialysis. About 150 patients will be enrolled in the studies, which are slated to begin in 2010.

The company notes on its Web site that ferumoxytol is currently being developed to treat iron-deficiency anemia in women with abnormal uterine bleeding and in patients with cancer and gastrointestinal diseases. Because of its potential to improve the visualization of blood vessels, ferumoxytol may also be useful as a diagnostic agent for vascular-enhanced magnetic resonance imaging to assess peripheral arterial disease.

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