What is the recommended dosing for intramuscular iron dextran (Inj Orofer, iron dextran) in a patient with iron deficiency anemia?

Iron Dextran (Orofer) Dosing for Iron Deficiency Anemia

For intramuscular iron dextran administration, give a mandatory 0.5 mL (25 mg) test dose first, then if no reaction occurs after at least 1 hour, administer daily doses not exceeding 0.5 mL (25 mg) for infants under 5 kg, 1.0 mL (50 mg) for children under 10 kg, and 2.0 mL (100 mg) for adults until the calculated total dose is reached. 1

Test Dose Requirements

All patients require a mandatory test dose before therapeutic dosing:

• Administer 0.5 mL (25 mg) intramuscularly in the buttock using proper Z-track technique 1
• Wait at least 1 hour before proceeding with therapeutic doses, as anaphylactic reactions typically occur within minutes but observation period should be extended 1, 2
• For pediatric patients ≤10 kg, the test dose is 10 mg; for 10-20 kg, use 15 mg 3

Daily Therapeutic Dosing Limits

Maximum daily IM doses by weight:

• Infants under 5 kg: 0.5 mL (25 mg iron) 1
• Children under 10 kg: 1.0 mL (50 mg iron) 1
• All other patients: 2.0 mL (100 mg iron) 1

Calculating Total Iron Requirement

Use the FDA-approved formula for total dose calculation:

For adults and children >15 kg:

• Dose (mL) = 0.0442 × (Desired Hb - Observed Hb) × LBW + (0.26 × LBW) 1
• This accounts for both hemoglobin restoration and iron store replacement 1

For children ≤15 kg:

• Dose (mL) = 0.0442 × (Desired Hb - Observed Hb) × W + (0.26 × W) 1
• Target hemoglobin for this group is 12 g/dL 1

Injection Technique

Proper IM administration is critical to avoid complications:

• Inject only into the upper outer quadrant of the buttock—never into the arm or exposed areas 1
• Use a 2-inch or 3-inch 19 or 20 gauge needle 1
• Employ Z-track technique (displace skin laterally before injection) to prevent subcutaneous leakage and staining 1
• Patient should bear weight on opposite leg if standing, or lie in lateral position with injection site uppermost 1

Alternative: Intravenous Administration

IV route offers advantages over IM, particularly for larger total doses:

• IV test dose: 0.5 mL over at least 30 seconds, wait 1 hour 1
• Individual IV doses up to 2 mL (100 mg) can be given daily at a rate not exceeding 50 mg (1 mL) per minute 1
• For hemodialysis or chronic kidney disease patients, single doses of 500-1000 mg diluted in 250 mL normal saline can be infused over 1 hour 4
• Total dose infusion (TDI) up to 1000 mg maximum is possible with low-molecular-weight iron dextran (INFeD), which has lower adverse event rates than high-molecular-weight formulations 5, 4

Important Safety Considerations

Critical caveats for iron dextran use:

• Anaphylactic reactions occur in fewer than 1% of administrations but can be life-threatening 3, 6
• History of multiple drug allergies increases risk of acute reactions 3
• Emergency medications (epinephrine, diphenhydramine, corticosteroids) must be immediately available 3
• Do not administer during active infection 5, 4
• Avoid use in first 4 months of life 1
• Do not mix with other medications or add to parenteral nutrition solutions 1

Monitoring Parameters

Track these parameters to assess response:

• Repeat iron studies (ferritin, transferrin saturation) 3-4 weeks after completing therapy 5
• Avoid measuring iron parameters within 7-14 days after IV iron administration for accurate results 4
• Target levels: transferrin saturation ≥20% and ferritin ≥100 ng/mL 3, 4
• Common adverse reactions include nausea (2.2%), headache, vomiting, chills, backache (1.1%), and fever/diarrhea (0.5%) 7

Clinical Context

IM iron dextran is appropriate when:

• Oral iron has failed due to intolerance, malabsorption, or ongoing blood loss 5, 2
• Patient cannot receive IV access or prefers IM route 1
• However, IV administration is generally preferred for convenience, allowing larger single doses and potentially faster repletion 4, 7

The total dose infusion approach via IV has demonstrated excellent safety profiles in multiple studies with no anaphylactic reactions in some series and faster hemoglobin recovery compared to divided dosing 7, 8, 2.