Chokri Ben Lamine: IV Iron Showdown – FCM vs Ferric Derisomaltose vs Iron Dextran

Chokri Ben Lamine, Assistant consultant at King Faisal Specialist Hospital and Research Center, shared a post on X:

“IV iron showdown – FCM vs ferric derisomaltose vs iron dextran 

Ferric carboxymaltose (FCM; Injectafer)

• Dose

Adults more than or equal to 50 kg: 750 mg IV ×2 doses at least 7 days apart, total 1500 mg/course; alternative 15 mg/kg up to 1000 mg as a single dose in some adults.

• Strengths and outcomes

Fast iron repletion, robust Hb/ferritin response, widely used when you want high-dose replacement with few visits.

Comparative data support efficacy similar to other modern IV irons.

• Key adverse effect

Biggest issue is hypophosphatemia. In the PHOSPHARE trials, hypophosphatemia was far more common with FCM than with ferric derisomaltose.

•  Other precautions

Watch for hypersensitivity, hypertension, extravasation skin staining, and monitor phosphate in at-risk patients or before repeat courses.

Correct pre-existing hypophosphatemia first.

•  Practical caution

Avoid casual repeat use in patients with prior FCM-related hypophosphatemia, osteomalacia risk, vitamin D deficiency, malabsorption, HHT, or other phosphate-wasting settings.

Ferric derisomaltose (FDI; Monoferric/Monofer)

• Dose

Adults more than or equal to  50 kg: 1000 mg IV once over at least 20 minutes.

Adults less than 50 kg: 20 mg/kg IV once. Repeat if IDA recurs.

• Strengths and outcomes

Excellent option when you want true single-visit full replacement.

In FERWON-IDA and FERWON-NEPHRO, it showed effective Hb improvement with low rates of serious/severe hypersensitivity, and the pooled safety analysis supported a favorable safety profile.

•  Major differentiator

Compared with FCM, FDI causes much less hypophosphatemia.

This is the cleanest evidence-based reason many clinicians prefer it when available.

• Adverse effects and precautions

Still monitor for hypersensitivity/anaphylaxis, infusion reactions, and extravasation with possible long-lasting brown discoloration. Give only where resuscitation capability exists.

•  Practical caution

Not ‘zero-risk’ for reactions, but in current practice it is often favored when you want high-dose iron with lower phosphate toxicity concern.

Iron dextran (INFeD / low-molecular-weight iron dextran)

• Dose

Dose is calculated to total iron deficit; the label allows incremental dosing until the calculated total is reached.

• Major limitation

This is the legacy product with boxed-warning hypersensitivity concern.

The U.S. label requires a 0.5 mL test dose before the first therapeutic dose and observation for at least 1 hour before giving the remainder of the first dose. Fatal reactions have occurred even after a tolerated test dose.

• Other adverse effects

Delayed reactions, arthralgia/myalgia, possible flare in rheumatoid arthritis, iron overload risk if diagnosis is wrong, and IM staining issues if given intramuscularly.

• Where it still fits

Useful when institutions are familiar with it or cost/formulary drives use, but from a modern practical standpoint it is usually less attractive than FCM/FDI because of the boxed warning and test-dose workflow.

 Bottom line choice

• Need 1 visit and lower hypophosphatemia risk leads to Ferric derisomaltose
•  Need effective high-dose iron and FDI not available leads to FCM, but think hard about phosphate
•  Using an older formulary option / specific institutional pathway: iron dextran, but respect the boxed warning added test dose added observation

 Landmark studies 

• Phosphare-ida 04 / phosphare-ida 05: ferric derisomaltose vs ferric carboxymaltose: much lower hypophosphatemia with derisomaltose.
• Ferwon-ida: ferric derisomaltose vs iron sucrose in IDA: effective Hb response and reassuring safety.
• Ferwon-nephro: ferric derisomaltose vs iron sucrose in non-dialysis CKD with IDA: effective and safe, supports single high-dose use.
  For iron dextran, modern practice is influenced more by current boxed-warning labeling and older comparative literature than by recent landmark superiority trials.”

Stay updated with Hemostasis Today.