Iron IV for IBD: Which Type is Best?

clinical-trial PMID: 36343979

Quick Summary: A recent study found that a specific type of intravenous (IV) iron, called ferric derisomaltose (FDI), caused fewer problems with phosphate levels compared to another type, ferric carboxymaltose (FCM), in people with iron deficiency anemia due to inflammatory bowel disease (IBD). Both types of iron helped with anemia.

What The Research Found

This research looked at two different IV iron treatments for people with IBD and low iron. The main finding was that:

FDI (ferric derisomaltose) was safer: It caused significantly fewer people to have low phosphate levels in their blood compared to FCM (ferric carboxymaltose). Low phosphate can lead to fatigue and other problems.

Both worked for anemia: Both FDI and FCM were effective at raising iron levels and improving anemia.

FDI may help with fatigue faster: People taking FDI seemed to feel less tired sooner than those taking FCM.

Study Details

Who was studied: 97 adults with IBD and iron deficiency anemia.

How long: The study lasted about 35 days.

What they took: Participants received either FDI or FCM through an IV, twice during the study. The dose was based on their weight and how low their hemoglobin was.

What This Means For You

If you have IBD and need IV iron, this study suggests:

Talk to your doctor: Discuss whether FDI might be a better option for you, as it may have fewer side effects related to phosphate levels.

Monitor your phosphate levels: If you are taking FCM, your doctor may want to check your phosphate levels regularly.

Report fatigue: Let your doctor know if you are feeling very tired, as it could be related to low phosphate.

Study Limitations

Short study: The study only looked at the effects for a short time (about a month), so we don't know the long-term effects.

Limited scope: The study focused on phosphate levels and fatigue, not other potential problems.

More research needed: More studies are needed to fully understand the differences between these two types of iron and how they affect people with IBD.

Key Findings

This study found that ferric derisomaltose (FDI) caused significantly fewer cases of hypophosphataemia (serum phosphate <2.0 mg/dL) compared to ferric carboxymaltose (FCM) in patients with iron deficiency anaemia (IDA) due to inflammatory bowel disease (IBD). While both treatments effectively corrected IDA, FCM was associated with a 51.0% incidence of hypophosphataemia versus 8.3% for FDI (adjusted risk difference: -42.8%, 95% CI -57.1% to -24.6%, p<0.0001). FCM also delayed fatigue improvement, which correlated with greater phosphate depletion.

Study Design

A randomized, double-blind clinical trial conducted across 20 European outpatient clinics (Austria, Denmark, Germany, Sweden, UK). Adults with IBD and IDA (n=97; 49 FDI, 48 FCM) received two intravenous doses at baseline and Day 35. The primary outcome was hypophosphataemia incidence from baseline to Day 35 in the safety analysis set. Secondary outcomes included mineral/bone homeostasis markers and fatigue scores.

Dosage & Administration

Both groups received identical haemoglobin- and weight-based dosing regimens. Iron was administered intravenously at baseline and Day 35. Specific dose amounts were not detailed in the summary, but dosing intervals and criteria aligned with standard clinical practice for correcting IDA in IBD.

Results & Efficacy

Hypophosphataemia: Occurred in 25/49 (51.0%) FCM patients vs 4/48 (8.3%) FDI patients (p<0.0001).
Anaemia Correction: Both formulations improved haemoglobin levels comparably.
Fatigue Scores: Improved in both groups, but FDI showed faster and greater recovery. Slower fatigue improvement correlated with larger phosphate decreases in FCM-treated patients.
Safety: No significant differences in adverse events, but FCM had a higher risk of transient phosphate depletion.

Limitations

Short duration (35 days), limiting insights into long-term phosphate stability or bone health effects.
Moderate sample size (n=97) and single-region recruitment (Europe), potentially affecting generalizability.
Mechanisms linking phosphate drops to fatigue were not mechanistically explored.
No direct measurement of bone mineral density or fracture risk; future studies needed to assess clinical consequences.

Clinical Relevance

For IBD patients requiring intravenous iron therapy, FDI may be preferable to FCM to reduce hypophosphataemia risk. Clinicians should monitor phosphate levels in patients receiving FCM, particularly those with prolonged fatigue. While both treatments correct IDA, the differential impact on phosphate homeostasis highlights the need to balance efficacy with metabolic safety. Further research is required to evaluate long-term risks (e.g., bone disease) and optimize dosing strategies for FDI. Patients may benefit from faster fatigue recovery with FDI, but individualized treatment decisions should consider comorbidities and phosphate status.

Source: PHOSPHARE-IBD Trial (2023)