What is the protocol for administering Ferrinject (intravenous iron) for iron deficiency anemia?

Ferrinject (Ferric Carboxymaltose) Administration Protocol

Ferrinject should be administered intravenously at doses of 500-1000 mg per infusion over 15 minutes, with the specific dose determined by body weight and hemoglobin level, and can be repeated at weekly intervals until the total iron deficit is corrected. 1

Dosing Regimen

Simple Fixed-Dose Protocol (Preferred)

The simplified dosing scheme is more effective and shows better compliance than calculated formulas 1, 2:

For patients with hemoglobin 100-120 g/L (women) or 100-130 g/L (men):

• Body weight <70 kg: 1000 mg total
• Body weight ≥70 kg: 1500 mg total 1

For patients with hemoglobin 70-100 g/L:

• Body weight <70 kg: 1500 mg total
• Body weight ≥70 kg: 2000 mg total 1

For patients with hemoglobin <70 g/L:

• Consider an additional 500 mg beyond the above calculations 1

Administration Schedule

• Maximum single dose: 1000 mg (or 500 mg if body weight <66 kg) 1, 3
• Infusion time: 15 minutes minimum 1
• Repeat interval: Weekly until total calculated dose is delivered 3, 2
• Maximum of 3 infusions typically required to complete treatment 2

Clinical Indications for Ferrinject

Intravenous iron (including Ferrinject) should be considered first-line in the following situations 1:

• Clinically active inflammatory bowel disease
• Previous intolerance to oral iron
• Hemoglobin <100 g/L (10 g/dL)
• Patients requiring erythropoiesis-stimulating agents
• Insufficient time before planned surgery (ideally >2 weeks) 4
• Functional iron deficiency (ferritin >100 μg/L but transferrin saturation <20%) 1

Safety Considerations

Pre-Administration Requirements

• Resuscitation facilities must be available during all intravenous iron administrations, as anaphylaxis can occur 1
• No test dose is required for ferric carboxymaltose 1
• Review manufacturer's contraindications and cautions 1

Adverse Effects Profile

• Incidence: 22-29% experience side effects, similar to other IV iron preparations 1
• No anaphylaxis reported in initial trials (as of 2011 guidelines) 1
• Common reactions: Headache, dizziness, nausea, abdominal pain, rash, injection-site reactions 3, 5
• Laboratory abnormality: Transient asymptomatic hypophosphatemia is the most common finding 5
• Better tolerated than oral iron due to fewer gastrointestinal side effects 3, 5

Monitoring and Follow-Up

Initial Response Assessment

• Monitor hemoglobin at 4 weeks: Expect an increase of ≥2 g/dL as an acceptable response 1
• Optimal timing: Patients receiving iron >2 weeks before surgery show 22% hemoglobin increase vs. only 5% if given <2 weeks prior 4

Long-Term Monitoring

After successful treatment 1:

• Monitor blood count every 3 months for the first year
• Then annually thereafter
• Check again if symptoms of anemia develop
• Re-treat when: Ferritin drops <100 μg/L or hemoglobin falls below 120 g/L (women) or 130 g/L (men) 1

Advantages Over Alternative IV Iron Preparations

Compared to iron sucrose (Venofer) and iron dextran (Cosmofer) 1:

• Higher single dose capacity: 1000 mg vs. 200 mg (iron sucrose) or requires 6-hour infusion (iron dextran)
• Shorter infusion time: 15 minutes vs. 10 minutes for only 200 mg (iron sucrose) or 6 hours (iron dextran)
• Fewer total administrations required: Maximum 3 infusions vs. up to 11 for iron sucrose 2
• No increased anaphylaxis risk compared to iron dextran which has 0.6-0.7% serious reaction rate 1
• Better compliance: The simplified dosing regimen shows superior efficacy and compliance compared to calculated iron sucrose regimens 2

Important Caveats

• The Ganzoni formula is inconvenient, prone to error, and underestimates iron requirements in clinical practice 1
• Hemoglobin rise at 12 weeks is similar between parenteral and oral iron, though the initial rise is more rapid with IV iron 1
• For iron deficiency without anemia, consider a minimum of 500-1000 mg total dose 1
• Cost consideration: Ferrinject is more expensive per gram of iron (£217.50/g) compared to iron sucrose (£70.80/g) or iron dextran (£79.70/g), but fewer administrations may offset costs 1