Ferrous fumarate
Ferrous fumarate
Generic Name
Ferrous fumarate
Mechanism
- Iron delivery: Provides ferrous (Fe²⁺) ions that are the biologically active form absorbed in the duodenum.
- Transport to marrow: Fe²⁺ enters enterocytes via the divalent‑metal transporter 1 (DMT1) and is exported into circulation by ferroportin, complexed with transferrin.
- Hemoglobin synthesis: The delivered iron is incorporated into heme for hemoglobin and myoglobin synthesis, replenishing erythrocyte production.
- Regulation: Hepcidin-mediated inhibition of ferroportin limits absorption when iron stores are adequate, ensuring homeostasis.
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Pharmacokinetics
| Parameter | Value |
| Absorption | Peak plasma levels 1–2 h post‑dose; maximized with a 30‑min fast. |
| Bioavailability | 1–2 % of oral dose available systemically due to limited solubility. |
| Distribution | ~70 % bound to transferrin; ~90 % to erythrocytes once incorporated into hemoglobin. |
| Metabolism | Minimal hepatic metabolism; iron is stored in ferritin or hemosiderin. |
| Elimination | Slow release via hepcidin‑regulated ferroportin; excess iron excreted by sloughing of enterocytes. |
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Indications
- Iron‑deficiency anemia (e.g., pregnancy, chronic blood loss).
- Repletion after surgical hemorrhage.
- Early‑onset pre‑eclampsia or anemia in pregnancy (to improve fetal iron status).
- Iron supplementation in chemotherapy‑related anemia (often combined with erythropoiesis‑stimulating agents).
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Contraindications
- Contraindications
- Known allergy to iron salts.
- Untreated hemochromatosis or other iron‑overload disorders.
- Warnings
- Gastrointestinal irritation: Nausea, constipation, and black stools are common.
- Hemodynamic instability: Rare risk of iron‑mediated oxidative stress in septic patients.
- Drug interactions: Calcium, antacids, thyroxine, and phenytoin reduce absorption; deferoxamine may precipitate iron–deferoxamine precipitate.
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Dosing
| Situation | Typical Dose | Frequency | Notes |
| Adults (iron‑deficiency anemia) | 30–50 mg elemental iron (≈ 240 mg ferrous fumarate) | 1–2 capsules daily | Administer 30 min before or 2 h after meals; avoid with dairy, tea, coffee. |
| Pregnancy | 30 mg elemental iron daily | 1 capsule | Aim for 30–60 mg if risk factors present. |
| Children ≥12 y | 1 mg/kg elemental iron | daily | Use pediatric formulations when available. |
| Pediatric <12 y | 1 mg/kg elemental iron | daily | Prefer liquid iron for dosing accuracy. |
Empty‑stomach administration enhances uptake. If GI tolerability limits dosing, split into morning and evening.
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Adverse Effects
- Common
- Nausea, dyspepsia, abdominal cramping.
- Constipation or mild diarrhea.
- Dark (black/purple) stool.
- Serious
- Iron overload (in rare cases of high cumulative doses).
- Hypersensitivity reactions: rash, itching, angioedema.
- Systemic reactions in patients with sepsis or acute intestinal injury.
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Monitoring
| Test | Frequency | Rationale |
| CBC & reticulocyte count | Weekly for first 4 wks, then biweekly | Gauge erythropoietic response. |
| Serum ferritin | Every 4–6 weeks | Evaluate iron stores; stop at >200 ng/mL to avoid overload. |
| Transferrin saturation (TSAT) | Every 4–6 weeks | Ideal target 20–30 %. |
| Serum iron | Every 2–3 months | Helps assess ongoing absorption. |
| Renal & liver panels | At baseline and as clinically indicated | Monitor for drug‑related organ stress. |
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Clinical Pearls
- Avoid ‘empty stomach’ myths: While fasting improves absorption, the risk of severe GI upset is higher; a light snack can balance tolerance and absorption.
- Co‑administration tricks: Use an orange‑juice dipstick (phosphoric‑acid‑rich) to soak the capsule for 30 min—transfers iron into a more absorbable aqueous form.
- Splitting dose strategy: Taking ½‑capsule twice daily can reduce constipation without compromising efficacy.
- Work‑up for hemochromatosis: If ferritin spikes >200 ng/mL early, order transferrin saturation and genetic testing before continuing therapy.
- Iron‑status synergy: Combine with vitamin C (ascorbate) 500 mg to further lift absorption; avoid it concurrent with calcium or antacids.
- Pregnancy nuance: Do not exceed 60 mg elemental iron daily without obstetric counsel; higher doses raise foetal iron‑related complications.
- Pharmacy note: Pack ferrous fumarate in blister packs labeled “Orange tablet with black edges” to distinguish from common iron complexes, reducing prescribing errors.
- Elderly advantage: Because ferrous fumarate is only 1–2 % bioavailable, elderly patients require careful dosing to avoid misdiagnosing anemia severity.
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