What are the different forms of intravenous (IV) iron and their recommended dosages?

Different Forms of Intravenous Iron and Their Dosing

Multiple IV iron formulations are available with varying dosing schedules, but modern high-dose preparations like ferric carboxymaltose, ferric derisomaltose, and low-molecular-weight iron dextran that allow 1000 mg single-dose administration are preferred over older formulations requiring multiple visits. 1

Available IV Iron Formulations

High-Dose Single Administration Products (Preferred)

• Ferric carboxymaltose (Injectafer): 750 mg IV over 15 minutes, given twice one week apart (total 1500 mg), or 1000 mg as a single dose for patients ≥50 kg 1, 2

  • Alternative dosing: 15 mg/kg up to maximum 1000 mg as single dose 2
  • For patients <50 kg: 15 mg/kg in two doses separated by at least 7 days 2
  • Critical caveat: Associated with hypophosphatemia in 50-74% of patients, potentially causing bone pain, osteomalacia, and fractures 3

• Ferric derisomaltose (iron isomaltoside): 1000 mg IV over 15 minutes as single infusion, or 500 mg IV push over 2 minutes 1, 4

  • Mean cumulative dose in trials: 1640 mg 4
  • Demonstrated superiority over iron sucrose for rapid hemoglobin improvement 4

• Low-molecular-weight iron dextran (INFed): 1000 mg IV over 1 hour as single total dose infusion 1

  • Requires mandatory test dose: 25 mg slow IV push, wait 1 hour before main dose 1, 5
  • Preferred over high-molecular-weight iron dextran (Dexferrum) due to significantly fewer adverse events 1, 5

• Ferumoxytol: 510 mg given as two doses, or 1020 mg as single dose 1

  • Special consideration: Acts as MRI contrast agent—consult radiology if MRI needed within 3 months 1

Multiple-Dose Products (Require More Frequent Administration)

• Iron sucrose: 200 mg IV over 60 minutes, repeated every 2-3 weeks 1

  • Alternative: 200 mg IV over 2-5 minutes 1
  • Maximum single dose: 300 mg (higher doses not recommended) 1
  • Test dose at physician discretion: 25 mg slow IV push 1, 5
  • Total course typically requires 5 doses for 1000 mg total 1
  • Well-tolerated with no anaphylactic reactions reported in primary care settings 6

• Ferric gluconate (Ferrlecit): 125 mg IV over 60 minutes, weekly for 8 doses (total 1000 mg) 1, 5

  • Individual doses above 125 mg not recommended based on trial data 1, 5
  • Test dose at physician discretion: 25 mg slow IV push or infusion 1, 5
  • Reactions generally less common and severe than iron dextran 7

Dosing Strategy Selection

Choose formulations allowing 1-2 total infusions to minimize patient burden and healthcare costs, unless specific contraindications exist. 1

When to Use Each Formulation:

• First-line for most patients: Ferric carboxymaltose or ferric derisomaltose for single-visit iron repletion 1, 4

  • Monitor serum phosphate in patients requiring repeat courses with ferric carboxymaltose 2

• Patients with previous hypersensitivity to one formulation: Switch to iron sucrose, which has excellent safety profile 7, 6

  • Slower infusion rates and proper dilution reduce reaction risk 7

• Cost-conscious settings: Low-molecular-weight iron dextran ($405 per 1000 mg course) or iron sucrose ($441.50 per 1000 mg course) are most economical 1

• Hemodialysis maintenance: Iron sucrose 100 mg three times weekly or ferric gluconate 125 mg weekly are standard 5, 8

Critical Safety Considerations

• Absolute contraindication: Active infection—do not administer IV iron 1, 5

• Hypersensitivity reactions: Occur in <1:200,000 administrations with modern formulations 1, 3

  • Most reactions are complement activation-related pseudo-allergy, not true allergy 1
  • Observe patients for at least 30 minutes post-infusion 2
  • For mild reactions: Stop infusion, restart at slower rate after 15 minutes 1
  • Avoid diphenhydramine—side effects mimic worsening reactions 1

• Test dose requirements: Mandatory only for iron dextran; strongly recommended for ferric gluconate and iron sucrose in patients with previous sensitivities or multiple drug allergies 1, 5

• Monitoring timing: Do not measure ferritin within 7-14 days after IV iron administration—levels are falsely elevated 1, 5

  • Repeat iron studies 8-10 weeks after treatment 1

Dosing for Specific Populations

Hemodialysis Patients:

• Maintenance: 250-1000 mg within 12-week periods 5
• Target: Transferrin saturation ≥20% and ferritin ≥100 ng/mL 5
• Monitor iron parameters every 3 months during maintenance 5

Pediatric Patients (≥1 year):

• Ferric carboxymaltose: 15 mg/kg in two doses separated by ≥7 days for patients <50 kg 2
• Iron dextran dosing varies by weight: 25 mg (≤10 kg), 50 mg (10-20 kg), 100 mg (≥20 kg) per dose 5

Inflammatory Bowel Disease:

• IV iron preferred over oral due to better gastrointestinal tolerability 9
• Iron sucrose demonstrated 20.8% discontinuation rate with oral iron vs 4.5% with IV 9