What is the dosing and administration of intravenous ferric carboxymaltose (iron replacement therapy) for a female patient with severe anemia (hemoglobin level less than 8 gm/dl)?

Ferric Carboxymaltose Administration for Severe Anemia (Hb <8 g/dL)

For a woman with hemoglobin less than 8 g/dL, administer ferric carboxymaltose 1000 mg intravenously on Day 1, followed by a second dose of 1000 mg at Week 6 if her weight is ≥70 kg, or 500 mg at Week 6 if her weight is <70 kg, diluted in 100 mL normal saline and infused over 15-30 minutes. 1

Mechanism of Action

Ferric carboxymaltose is a macromolecular ferric hydroxide carbohydrate complex that allows controlled release of elemental iron after injection. 2 The carbohydrate shell stabilizes the ferric hydroxide core, enabling delivery of iron to the reticuloendothelial system, where it is subsequently transferred to ferritin and transferrin with minimal risk of releasing large amounts of ionic iron into the serum. 3 Red blood cell uptake of iron from ferric carboxymaltose ranges from 91% to 99% in iron-deficient patients within 24 days of administration. 1

Dosing Protocol for Severe Anemia (Hb <8 g/dL)

Initial Dosing

• For patients ≥50 kg: Administer 750 mg intravenously on two occasions separated by at least 7 days, for a total cumulative dose of 1,500 mg per course. 1
• Alternative single-dose regimen: 15 mg/kg body weight up to a maximum of 1,000 mg may be administered as a single dose per course in adults. 1
• For patients <50 kg: Administer 15 mg/kg body weight intravenously in two doses separated by at least 7 days per course. 1

Specific Dosing for Severe Anemia

Since your patient has Hb <8 g/dL (which falls into the <10 g/dL category), the FDA-approved dosing for heart failure patients provides the most relevant guidance, even if she doesn't have heart failure, as this addresses severe anemia specifically:

• Weight <70 kg with Hb <10 g/dL: 1,000 mg on Day 1, followed by 500 mg at Week 6. 1
• Weight ≥70 kg with Hb <10 g/dL: 1,000 mg on Day 1, followed by 1,000 mg at Week 6. 1

Administration Procedure

Preparation

• Dilute ferric carboxymaltose in 100 mL of normal saline before administration. 2
• When diluting for infusion, use no more than 250 mL of sterile 0.9% sodium chloride, ensuring the concentration is not less than 2 mg of iron per mL. 1
• The diluted solution is stable for 72 hours at room temperature when concentrations range from 2 to 4 mg iron/mL. 1
• Inspect for particulate matter and discoloration prior to administration. 1

Infusion Method (Preferred)

• Administer the diluted solution over 15-30 minutes. 2, 1
• Monitor the patient for adverse effects during and for at least 30 minutes following each infusion. 2

Alternative: Undiluted Slow IV Push

• For doses of 500-750 mg: Administer at approximately 100 mg (2 mL) per minute. 1
• For 1,000 mg doses: Administer as a slow IV push over 15 minutes. 1

Critical Safety Monitoring

During Administration

• Ensure proper IV line placement to avoid extravasation, as brown discoloration at the extravasation site may be long-lasting. 1
• If extravasation occurs, discontinue administration at that site immediately. 1
• Observe for hypersensitivity reactions for at least 30 minutes post-infusion. 2

Contraindications

Do not administer if:

• Hemoglobin >15 g/dL 2
• Known hypersensitivity to ferric carboxymaltose or its excipients 2
• Anemia not attributed to iron deficiency 2
• Evidence of iron overload 2

Special Cautions

• Hypophosphatemia risk: Ferric carboxymaltose causes treatment-emergent hypophosphatemia in up to 58% of patients, though most cases are asymptomatic and resolve without intervention. 2 Check serum phosphate levels if repeat dosing is needed within 3 months. 1
• Active infection: Use with caution in patients with acute or chronic infection; stop treatment if bacteremia develops. 2
• Drug allergies: Use with caution in patients with severe asthma, eczema, or atopic allergies. 2

Expected Response and Follow-Up

Timeline for Hemoglobin Response

• Hemoglobin concentrations should increase within 1-2 weeks of treatment. 2
• Expect a hemoglobin increase of 1-2 g/dL within 4-8 weeks of therapy. 2
• In clinical trials, 82% of patients achieved a hemoglobin increase ≥2 g/dL with ferric carboxymaltose. 4

Laboratory Monitoring

• Do not check iron parameters within 4 weeks of administration, as circulating iron interferes with assays, leading to inaccurate results. 2, 5
• Perform complete blood count and iron parameters (ferritin, transferrin saturation) 4-8 weeks after the last infusion. 2
• For severe anemia, monitor hemoglobin every 4 weeks until normalized. 5

Maintenance Dosing

• Re-evaluate iron status at 3 months after initial treatment. 2
• Consider re-treatment when ferritin drops below 100 ng/mL or hemoglobin falls below normal range (12 g/dL for women). 5

Advantages Over Oral Iron in Severe Anemia

• Ferric carboxymaltose delivers up to 1,000 mg of iron in a single 15-minute infusion, compared to oral iron's limited absorption of 10-20 mg daily. 5
• Achieves more rapid and complete iron repletion than oral formulations. 5
• Avoids gastrointestinal side effects that occur with oral iron therapy. 5
• In patients with Hb <8 g/dL, the urgency of correction makes intravenous iron the superior choice over oral therapy. 2