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Kidney Week

Abstract: PO0283

A Novel, Fast-Acting Iron Sucrose Formulation for CKD Patients with Iron Deficiency Anemia

Session Information

Category: Anemia and Iron Metabolism

  • 200 Anemia and Iron Metabolism


  • Cook, Charles M., CMC SQUARED, Southlake, Texas, United States
  • Singh, Bhupinder, University of California Irvine, University of California Irvine, Irvine, CA, US, Department of Medicine, Irvine, California, United States
  • Ruiz, Stacey, Renibus Therapeutics, Southlake, Texas, United States
  • Guillem, Alvaro F., Renibus Therapeutics, Southlake, Texas, United States

Intravenous (IV) iron is commonly used to treat iron deficiency anemia in patients with chronic kidney disease (CKD). We report the results of the physicochemical and safety profile of RBT-3, a novel iron sucrose formulation, which was assessed in a Phase 1b study conducted in healthy volunteers and subjects with chronic kidney disease (CKD) Stage 3 or 4.


Analytical testing was conducted to examine the physicochemical profile of RBT-3. Safety of RBT-3 was assessed in a Phase 1b study in healthy volunteers and subjects with CKD. RBT-3 was administered IV as a single dose of 120, 240, or 360 mg. Plasma and urine ferritin were measured at baseline, then 2 h (plasma) or 24 h (urine) through 168 h post-treatment to assess clinical response.


RBT-3 particle size is similar to commercially available iron sucrose. However, RBT-3 has a lower molecular weight and higher water content than similar IV iron formulations, suggesting faster uptake and greater solubility, respectively. RBT-3 also has a negative Zeta potential, demonstrating low cytotoxic potential. The quantity of labile iron in RBT-3 is 1.48%, suggesting very low availability of free inorganic iron hydroxide, with a low cytotoxic potential. Furthermore, Fe2+, which is associated with oxidative stress, is present in much lower quantities in RBT-3 (3.4%) compared to commercially available iron sucrose (15.8%).

In this Phase 1b study of RBT-3, 18 subjects were enrolled; 6 subjects (3 healthy volunteers and 3 subjects with CKD) randomized to 3 cohorts received a single dose of RBT-3 at 120, 240, or 360 mg. Mean age was 60.3 years; 66.7% of the subjects were female. Dose-dependent increases in plasma ferritin were observed in all subjects within 2 h of treatment and reached statistical significance by 8-12 h. Urine levels were increased at 24 h. Both plasma and urine ferritin levels remained elevated through 168 h (7 days). No treatment-related adverse events (AEs) were observed, and no serious AEs (SAEs) were reported.


RBT-3 represents a novel iron sucrose formulation with desirable physicochemical characteristics that makes it a fast-acting mediator of iron hemodynamics. This is the first report of ferritin level increases within only 2 h by an iron formulation. RBT-3 is safe and well tolerated in healthy volunteers and subjects with CKD at a single dose up to 360 mg.


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