The pharmaceutical drug Injectafer (generic name: ferric carboxymaltose), an iron carbohydrate complex used to treat iron deficiency anemia, has been linked to severe hypophosphatemia (HPP) – a dangerously low level of phosphorus in the blood that can cause life-threatening complications.
Severe Hypophosphatemia Can Be Life-Threatening
Iron deficiency anemia occurs when the body lacks sufficient iron. Injectafer is an iron deficiency anemia treatment used in adult patients who have an intolerance or unsatisfactory response to oral iron. The drug is injected intravenously by a healthcare professional, often in two doses, approximately seven days apart.1
Injectafer has been shown to dramatically reduce the amount of phosphate (phosphorus) in the body, leading to severe hypophosphatemia. Symptoms of severe HPP include extreme fatigue, muscle weakness and confusion, and left untreated, severe HPP can cause seizures, respiratory failure, heart failure, rhabdomyolysis, and osteomalacia.2 Complications involving severe HPP can even lead to coma and death.3
Studies Show Injectafer Increases Risk of Severe Hypophosphatemia
Clinical studies involving Injectafer overwhelmingly point to Injectafer’s propensity to cause severe HPP at rates drastically higher than its competitor iron supplements.
For example, a study published in February 2020 found that 73-74% of those given Injectafer developed hypophosphatemia (measured as a serum phosphate level of 2.0 mg/dL or less), while only 8% of those given another iron infusion drug called Monoferric developed hypophosphatemia.4 Severe hypophosphatemia (measured as a serum phosphate level of 1.0 mg/dL or less) occurred in 11.3% of those treated with Injectafer, but did not develop in those treated with Monoferric.5
Another study published in 2018 reported that over half of those treated with Injectafer developed severe hypophosphatemia (serum phosphate measured at less than 2.0 mg/dl ) and 10% developed extreme hypophosphatemia (serum phosphate measured at less than 1.3 mg/dl), while less than 1% of those treated with Feraheme developed severe hypophosphatemia and none developed extreme hypophosphatemia.6
Injectafer Label Changed in February 2020 to Warn of “Symptomatic Hypophosphatemia”
Despite all of the medical studies demonstrating the disproportionate rates of severe and extreme hypophosphatemia among Injectafer users, the manufacturers of Injectafer failed to adequately warn of the dangerous nature of Injectafer. Prior to February 19, 2020, the label did not mention severe or symptomatic hypophosphatemia as a potential risk of using the drug. In February 2020, the label was updated to include a warning for “Symptomatic Hypophosphatemia.”7 The label still does not address the severity or the high rate of hypophosphatemia that Injectafer can cause.
1 See https://injectaferhcp.com/.
2 Imel EA, Econs MJ. Approach to the hypophosphatemic patient. J Clin Endocrinol Metab. 2012;97(3):696‐706. doi:10.1210/jc.2011-1319.
3 Wang et al., Impact of hypophosphatemia on outcome of patients in intensive care unit: a retrospective cohort study. BMC Anesthesiol. 2019 May 24;19(1):86. doi: 10.1186/s12871-019-0746-2.
4 Wolf M, et al., Effects of Iron Isomaltoside vs Ferric Carboxymaltose on Hypophosphatemia in Iron-Deficiency Anemia: Two Randomized Clinical Trials, JAMA. 2020; 323(5)423-443 (Feb. 2020).
5 Id.
6 Wolf M, et al. Randomized trial of intravenous iron-induced hypophosphatemia. JCI Insight. 2018;3(23) (Dec. 2018).
7 Injectafer [package insert]. Shirley, NY: American Regent, Inc. February 2020.
