Iron-magnesium hydroxycarbonate (fermagate): a novel non-calcium-containing phosphate binder for the treatment of hyperphosphatemia in chronic hemodialysis patients

Abstract

Background and objectives: This phase II study tested the safety and efficacy of fermagate, a calcium-free iron and magnesium hydroxycarbonate binder, for treating hyperphosphatemia in hemodialysis patients.

Design, setting, participants, & measurements: A randomized, double-blind, three-arm, parallel-group study compared two doses of fermagate (1 g three times daily or 2 g three times daily with placebo). Sixty-three patients who had been on a stable hemodialysis regimen for > or =3 mo were randomized to the treatment phase. Study medication was administered three times daily just before meals for 21 d. The primary endpoint was reduction in serum phosphate over this period.

Results: In the intention-to-treat analysis, mean baseline serum phosphate was 2.16 mmol/L. The fermagate 1- and 2-g three-times-daily treatment arms were associated with statistical reductions in mean serum phosphate to 1.71 and 1.47 mmol/L, respectively. Adverse event (AE) incidence in the 1-g fermagate arm was statistically comparable to the placebo group. The 2-g arm was associated with a statistically higher number of patients reporting AEs than the 1-g arm, particularly gastrointestinal AEs, as well as a higher number of discontinuations, complicating interpretation of this dose's efficacy. Both doses were associated with elevations of prehemodialysis serum magnesium levels.

Conclusions: The efficacy and tolerability of fermagate were dose dependent. Fermagate showed promising efficacy in the treatment of hyperphosphatemia in chronic hemodialysis patients as compared with placebo in this initial phase II study. The optimal balance between efficacy and tolerability needs to be determined from future dose-titration studies, or fixed-dose comparisons of more doses.

Figure 1.

Molecular structure of fermagate.

Figure 2.

Schematic of study design.

Figure 3.

Summary of patient disposition in the study, including all patients screened (see ”Statistical and Analytical Plans” for definition of populations).

Figure 4.

Mean serum phosphate values during the current therapy, washout, study, and follow-up periods for the ITT population: primary efficacy variable. (Serum phosphate level during treatment with 1- and 2-g fermagate three times daily was significantly lower than with either washout or in comparison with placebo-treated patients.)