What is the recommended dosage and treatment duration for iron deficiency using FeO (Ferrous Oxide) spansule?

FeO Spansule for Iron Deficiency: Dosing and Duration

For iron deficiency anemia, start with ferrous sulfate 200 mg once daily (or every other day if not tolerated), and continue treatment for 3 months after hemoglobin normalizes to replenish iron stores. 1

Initial Treatment Approach

Ferrous sulfate remains the gold standard for oral iron therapy due to its optimal absorption, efficacy, and cost-effectiveness. 1, 2, 3 While you asked about ferrous oxide (FeO) spansules specifically, current guidelines prioritize standard ferrous sulfate formulations over modified-release preparations.

Recommended Dosing Strategy

• Start with 50-100 mg elemental iron once daily (ferrous sulfate 200 mg contains 65 mg elemental iron). 1
• Once-daily dosing is as effective as multiple daily doses because iron absorption triggers hepcidin elevation, which reduces subsequent iron absorption by 35-45% when taken more frequently. 1
• Alternate-day dosing may be considered if daily dosing is not tolerated, as this significantly increases fractional iron absorption. 1

Treatment Duration

• Continue oral iron for approximately 3 months after hemoglobin normalizes to ensure adequate repletion of marrow iron stores. 1
• Monitor hemoglobin response within the first 4 weeks to confirm treatment effectiveness. 1
• Expect hemoglobin to rise by 2 g/dL after 3-4 weeks of appropriate therapy. 1

Important Caveats About Modified-Release Formulations

Modified-release (MR) or "spansule" formulations are generally not recommended as first-line therapy. 1 These preparations:

• Release iron beyond the duodenum where absorption is optimal
• Are more expensive than standard ferrous sulfate tablets
• Have not demonstrated superior efficacy in clinical guidelines 1

Alternative Options if Standard Therapy Fails

If ferrous sulfate is not tolerated at standard doses:

• Reduce to one tablet every other day before switching formulations. 1
• Consider alternative ferrous salts (ferrous fumarate 210 mg or ferrous gluconate 300 mg). 1
• Ferric maltol (30 mg twice daily) may be better tolerated in patients with previous intolerance to traditional iron salts. 1

When to Consider Parenteral Iron

Switch to intravenous iron when oral iron is contraindicated, ineffective, or not tolerated after trying at least two oral preparations. 1 Specific indications include:

• Intolerance to oral iron despite dose reduction or formulation changes 1, 3
• Inadequate response to oral therapy 4, 3
• Active inflammatory bowel disease with compromised absorption 4, 3
• Chronic kidney disease or heart failure 4, 3
• Need for rapid iron repletion (e.g., pre-operative) 5, 3
• Hemoglobin below 10 g/dL requiring faster correction 4

Follow-Up Monitoring

After successful iron repletion:

• Monitor blood count every 3-6 months initially for the first year to detect recurrent iron deficiency. 1
• Re-check after another year if stable. 1, 4
• Give additional oral iron if hemoglobin or MCV falls below normal during follow-up. 1

Common Pitfalls to Avoid

• Don't use multiple daily doses as first-line strategy—once daily or alternate-day dosing optimizes absorption and tolerability. 1
• Don't stop treatment when hemoglobin normalizes—continue for 3 additional months to replenish stores. 1
• Don't assume treatment failure before 3-4 weeks—allow adequate time for hemoglobin response. 1
• Don't persist with poorly tolerated oral iron—consider dose reduction, alternate-day dosing, or parenteral iron rather than accepting non-compliance. 1, 6