Introduction
Iron deficiency anemia (IDA) is the most common nutritional disorder worldwide, affecting nearly 1.9 billion people. Pregnant women, children, and patients with chronic illnesses are most vulnerable. Although oral iron is the first-line treatment, many patients develop gastrointestinal side effects or fail to respond adequately. Intravenous (IV) iron sucrose has emerged as an effective alternative for rapid replenishment of iron stores and correction of anemia.
This paper reviews the pharmacology, clinical applications, benefits, limitations, and safety of intravenous iron sucrose.
Pharmacology of Iron Sucrose
Iron sucrose is a water-soluble complex of polynuclear iron (III) hydroxide and sucrose.
- Administration: Intravenous infusion or slow IV injection.
- Action: Direct entry into circulation bypasses gastrointestinal absorption.
- Mechanism: Iron binds transferrin, delivered to bone marrow for hemoglobin synthesis; excess stored in ferritin.
- Excretion: Minimal renal clearance; most iron used for erythropoiesis.
This controlled release minimizes free iron toxicity and allows rapid correction of deficiency.
Clinical Indications
IV iron sucrose is indicated in patients with:
- Iron deficiency anemia (IDA) unresponsive to or intolerant of oral iron.
- Chronic kidney disease (CKD): Particularly dialysis patients on erythropoietin.
- Pregnancy: Moderate-to-severe anemia requiring fast correction.
- Inflammatory bowel disease (IBD): Where absorption of oral iron is impaired.
- Cancer and chemotherapy: To address anemia caused by malignancy or treatment.
- Surgery: Preoperative optimization to reduce transfusion needs.
Dosage and Administration
The total required iron dose is calculated based on hemoglobin deficit and body weight:
Formula: Iron (mg) = Body weight (kg) × (Target Hb – Actual Hb) × 2.4 + 500 mg (iron stores).
- Typical dose: 200 mg per infusion, 2–3 times weekly.
- Infusion: Diluted in 100 mL saline, over 30 minutes.
- Maximum single dose: 200–300 mg.
Advantages Over Oral Iron
- Rapid replenishment of iron stores.
- Fewer gastrointestinal side effects (e.g., constipation, nausea).
- Better compliance due to less frequent dosing.
- Effective in malabsorption syndromes.
- Suitable in chronic inflammatory states.
Efficacy Evidence
- Pregnancy: Studies show Hb rise of 2–3 g/dL within 4–6 weeks, superior to oral iron.
- CKD: Enhances erythropoietin response and reduces transfusion requirements.
- IBD: Corrects anemia without worsening gastrointestinal symptoms.
Overall, IV iron sucrose demonstrates faster and more reliable improvement in hemoglobin and ferritin than oral therapy.
Safety Profile
Compared to older preparations (e.g., iron dextran), iron sucrose has an excellent safety record.
Common Side Effects:
- Headache
- Nausea
- Hypotension
- Injection site pain
Rare Side Effects:
- Hypersensitivity reactions (rare, less frequent than with dextran).
- Iron overload with excessive dosing.
Its tolerability makes it suitable for pregnancy, pediatrics (severe cases), and elderly patients.
Special Considerations
- Pregnancy: Safe in 2nd and 3rd trimesters; improves maternal Hb and birth outcomes.
- Children: Used in severe anemia when oral therapy fails.
- Elderly: Beneficial in those with chronic illnesses or poor absorption.
Global Health Relevance
- Anemia affects ~40% of pregnant women and ~42% of children under five globally (WHO, 2021).
- Oral iron remains central in public health programs due to cost, but IV iron sucrose is increasingly used in hospitals for high-risk groups.
- It plays a vital role in reducing transfusions, improving quality of life, and lowering morbidity.
Limitations
- Requires trained staff and healthcare facilities.
- Higher cost than oral iron.
- Risk of iron overload if dosing is not monitored.
- Multiple infusions needed for complete correction.
Conclusion
Intravenous iron sucrose is a safe and effective therapy for iron deficiency anemia, especially when oral iron fails or rapid correction is needed. Its role is well established in pregnancy, CKD, IBD, cancer-related anemia, and perioperative care. While oral iron remains important for population-level prevention, IV iron sucrose offers a crucial option for vulnerable patients.
With proper monitoring and rational use, it can significantly reduce anemia-related complications and improve patient outcomes worldwide.
References
- Auerbach, M., & Macdougall, I. C. (2014). Safety of intravenous iron formulations: facts and folklore. Blood Transfusion, 12(3), 296–300. https://doi.org/10.2450/2013.0164-13
- Bayoumeu, F., Subiran-Buisset, C., Baka, N. E., Legagneur, H., Monnier-Barbarino, P., & Laxenaire, M. C. (2002). Iron therapy in iron deficiency anemia in pregnancy: intravenous versus oral. American Journal of Obstetrics and Gynecology, 186(3), 518–522. https://doi.org/10.1016/S0301-2115(05)80402-6
- Macdougall, I. C. (2009). Intravenous iron therapy in chronic kidney disease: recent evidence and future directions. Clinical Kidney Journal, 2(Suppl 1), i16–i23. https://doi.org/10.1093/ndtplus/sfp013
- Milman, N. (2011). Iron prophylaxis in pregnancy – general or individual and in which dose? Annals of Hematology, 90(12), 1247–1253. https://doi.org/10.1007/s00277-011-1279-y
- World Health Organization. (2021). Global anaemia estimates. Retrieved from https://www.who.int/data/gho/data/themes/topics/anaemia
