Efficacy and Safety of Low Molecular Weight Iron Dextran (LMWID) Vs. Ferumoxytol in Treating Iron Deficiency Anemia

Introduction: Iron deficiency anemia is the most common form of anemia and hematologic problem worldwide. Treatment options include oral or intravenous (IV) iron replacement. Although oral iron is commonly employed as first-line therapy, many studies suggest that IV iron more effective and associated with better quality of life when compared to oral iron. Yet, adverse infusion reactions are possible. Several forms of IV iron are used in clinical practice, including low molecular weight iron dextran (LMWID), ferumoxytol, ferric gluconate, iron sucrose, and ferric carboxymaltose. We sought to compare the efficacy and safety of LMWID and ferumoxytol, the two most frequently used products at our center.

Methods: A retrospective cohort analysis was conducted using internal pharmacy records. Adults with an ICD-10 diagnosis of iron deficiency anemia treated with LMWID or ferumoxytol from 2018 to 2019 were identified. Records were reviewed for demographics, comorbidities, allergies, type and frequency of iron administered. Outcomes of interest were comparisons of baseline and post-treatment hemoglobin [Hgb] and ferritin levels and adverse events (AEs) following infusion.

Results: In total 55 patients received one of the two included iron preparations. Of the 40 cases of iron deficiency treated with LMWID, only 4 patients (10%) received a second dose. Of the first LMWID infusions (dose of 1000 mg), all patients demonstrated an increase in Hgb from a mean of 12.21 to 13.15 within an average of 2.75 months. Mean ferritin levels went from 28.34 pre-treatment to 231.14 post-treatment, within an average of 3.26 months. 2 patients (5%) received premedication, one with diphenhydramine or promethazine, based on prior history of an AE. AEs were documented in 3 patients (7.5%) and included arm swelling, dysphagia with globus sensation, and nausea. No patients received premedication prior to ferumoxytol infusion. Those receiving ferumoxytol demonstrated an increase in hemoglobin from a mean of 10.25 to 12.17 within an average of 4.2 months. Ferritin increased from baseline 75.93 to 150.33 within 3 months. AE of diarrhea and nausea were reported in only one patient (6.67%) upon second infusion of ferumoxytol. No patient in either group experienced AEs requiring hospitalization, nor did any patient develop severe hypersensitivity reactions, hypotension, or hypophosphatemia.

Discussion: In our retrospective cohort, LMWID or ferumoxytol for treatment of iron deficiency were well tolerated with minimal AEs, limited to arm swelling, dysphagia and nausea in 3 patients. Those treated with ferumoxytol experienced similarly few AEs, with only one patient developing transient diarrhea and nausea. Hesitancy to utilize IV iron has persisted due to concerns for potential side effects including anaphylaxis. Our encouraging results provide additional evidence for the efficacy and safety of LMWID and furomoxytol, and should help to assuage fears that IV iron might be poorly tolerated or ineffective.