ferrous fumarate
iron supplement· Brands: Fersamal, PalaferPO
Mechanism of action
Ferrous fumarate is an oral iron preparation. It provides elemental iron, which is essential for the production of haemoglobin. In the bone marrow, iron is incorporated into haemoglobin during erythropoiesis, enabling red blood cells to carry oxygen. Iron also forms part of myoglobin in muscle and of various enzymes involved in cellular respiration. Supplementation of ferrous fumarate corrects iron deficiency by replenishing body iron stores.
Pharmacokinetics
Absorption of iron from ferrous fumarate occurs mainly in the duodenum and upper jejunum. Absorption is enhanced by vitamin C and gastric acid, and reduced by food, tea, coffee, and some medications. Once absorbed, iron is transported in the blood bound to transferrin and stored as ferritin or haemosiderin, mainly in the liver, spleen, and bone marrow. Small amounts are lost via desquamation of intestinal mucosa, sweat, and urine. The ferrous fumarate salt has a high elemental iron content, approximately 33% by weight.
Indications & dosing
Treatment of iron deficiency anaemia
In divided doses. Ferrous fumarate 200 mg contains 65 mg elemental iron.
- adult · PO: 200–400 mg daily · In divided doses. Ferrous fumarate 200 mg contains 65 mg elemental iron.
Prophylaxis of iron deficiency anaemia
May be used in pregnancy. Ferrous fumarate 200 mg contains 65 mg elemental iron.
- adult · PO: 200 mg daily · May be used in pregnancy. Ferrous fumarate 200 mg contains 65 mg elemental iron.
Treatment of iron deficiency anaemia in children
Dose expressed as elemental iron. Ferrous fumarate 200 mg contains 65 mg elemental iron. Give in divided doses.
- pediatric · PO: 3–6 mg/kg/day daily · Dose expressed as elemental iron. Ferrous fumarate 200 mg contains 65 mg elemental iron. Give in divided doses.
Contraindications & precautions
- Hypersensitivity to ferrous fumarate or any component of the preparation · Anaphylaxis has been reported rarely.
- Iron overload conditions (e.g. haemochromatosis, haemosiderosis) · Avoid iron supplementation in these conditions to prevent further iron accumulation.
- Anaemias not due to iron deficiency (e.g. haemolytic anaemia, megaloblastic anaemia) · Iron may exacerbate the underlying disorder or cause iron overload if not required.
- Active peptic ulcer, ulcerative colitis, or regional enteritis · Oral iron can worsen gastrointestinal symptoms; consider parenteral iron if treatment is necessary.
- Use with caution in patients with a history of peptic ulcer, inflammatory bowel disease, or gastrointestinal bleeding.
- Administer iron supplements with or after meals to reduce gastrointestinal irritation, although this may decrease absorption.
- Advise patients that stools may darken; this is harmless but may affect interpretation of faecal occult blood tests.
- Keep out of reach of children; iron overdose is potentially fatal.
- Avoid concurrent administration with antacids, tetracyclines, or iron-binding agents; separate by at least 2-3 hours to enhance absorption.
Adverse effects
- Constipation
- Nausea
- Diarrhoea
- Abdominal pain
- Dark stools (conferring a black color)
- Allergic reactions (urticaria, angioedema, anaphylaxis)serious
- Iron overload (with prolonged excessive dosing)serious
Interactions
- levothyroxinemoderateAdminister levothyroxine and ferrous fumarate at least 4 hours apart to minimise the interaction. Monitor serum TSH and thyroid function tests, particularly when starting or stopping iron therapy, and adjust the levothyroxine dose as necessary. If separation is not feasible, consider alternative iron formulations or consult a specialist.
Monitoring, pregnancy & toxicity
- Haemoglobin · Baseline, then as clinically indicated
- Serum ferritin · Baseline, then every 4-8 weeks during treatment
- Serum iron and transferrin saturation · As clinically indicated
- Gastrointestinal symptoms · During treatment
- Pregnancy: Ferrous fumarate is generally safe and recommended for iron deficiency anaemia in pregnancy. It is not associated with fetal harm. Use at the lowest effective dose, and avoid excessive iron supplementation above requirements.
- Toxicity: Acute iron overdose: early symptoms include nausea, vomiting, abdominal pain, and haematemesis. Later signs include pallor, cyanosis, lethargy, metabolic acidosis, and cardiovascular collapse. · Patients with significant ingestion require emergency assessment. Decontamination with gastric lavage and whole bowel irrigation. Administer desferrioxamine for severe toxicity, including those with serum iron > 500 microg/dL or features of systemic toxicity.
- Toxicity: Chronic iron overload from repeated large doses may cause organ dysfunction. Symptoms include fatigue, joint pain, and hepatomegaly. · Stop iron supplementation and assess iron stores. Consider referral for chelation therapy (e.g. deferoxamine) if severe.
Antidotes & reversal
- Deferoxamine · Chelation for significant toxicity; calculate elemental iron dose (fumarate is ~33% iron).
Clinical notes
Ferrous fumarate is used for the treatment and prevention of iron deficiency anaemia, including during pregnancy and lactation. Common adverse effects include gastrointestinal upset, constipation, black stools, and nausea. To optimise absorption, it should be taken on an empty stomach, but it may be taken with food to reduce gastrointestinal irritation. Caution is required in patients with haemochromatosis or other iron overload disorders. Iron overdose is dangerous, particularly in children; keep out of reach. Avoid concurrent administration with antacids, tetracyclines, or quinolones. Monitor response with blood counts and ferritin levels.
Log in to read the full ferrous fumarate monograph
A free account unlocks the complete drug reference, the interaction checker, prescription practice and every other learning tool.
BNF; local formulary