Labile iron in parenteral iron formulations: a quantitative and comparative study

Area of Science:

• Biochemistry
• Pharmacology
• Hematology

Background:

• Intravenous (IV) iron administration is associated with iron-mediated oxidative stress, neutrophil dysfunction, and increased bacterial growth.
• These adverse effects are often attributed to a labile or bioactive iron fraction present in IV iron formulations.

Purpose of the Study:

• To quantify and compare the labile iron fraction across different classes of IV iron agents.
• To assess the in vitro iron donation capacity to transferrin (Tf) for various IV iron preparations.

Main Methods:

• Serum samples with added ferric gluconate, iron sucrose, or iron dextran were processed through alumina columns to isolate Tf-bound iron.
• The amount of iron donated to Tf was calculated by measuring Tf-bound iron in eluates and comparing it to control samples.
• Percent iron donation to Tf was determined relative to the concentration and type of IV iron agent added.

Main Results:

• Tf-bound iron increased proportionally with the concentration and type of IV iron agent added (P<0.001).
• The mean percent iron donation to Tf ranged from 2.5% to 5.8%, with ferric gluconate showing the highest donation, followed by iron sucrose and then iron dextran preparations.
• Statistically significant differences in iron donation were observed between ferric gluconate and both iron dextran agents, and between iron sucrose and iron dextran-Dexferrum (P<0.05).

Conclusions:

• A small but significant fraction (approximately 2-6%) of iron from common IV iron compounds is available for in vitro iron donation to Tf.
• This labile iron fraction is a potential contributor to the bioactive iron effects observed in patients receiving IV iron therapy.