Ferric citrate

Effect of Phosphate Binders and a Dietary Iron Supplement on the Pharmacokinetics of a Single Dose of Vadadustat in Healthy Adults

Vadadustat is a hypoxia-inducible factor prolyl-hydroxylase inhibitor being developed for the treatment of anemia in patients with chronic kidney disease. Sequelae of chronic kidney disease include hyperphosphatemia and anemia, which are frequently treated with phosphate binders and iron supplements, respectively. Two studies evaluating the pharmacokinetics, safety, and tolerability of a single oral dose of vadadustat coadministered with a phosphate binder or iron supplement were conducted in healthy adult participants. In study 1, 54 healthy women and men were administered vadadustat (300 mg) alone and 1 hour before, concurrently with, or 2 hours after a phosphate binder (sevelamer carbonate 1600 mg, calcium acetate 1334 mg, or ferric citrate 2000 mg). In study 2, 10 healthy men were administered vadadustat (450 mg) alone and concomitantly with the oral iron supplement ferrous sulfate (325 mg [equivalent to 65 mg of elemental iron]). Vadadustat exposure was reduced by coadministration with sevelamer carbonate, calcium acetate, ferric citrate, or ferrous sulfate. Geometric least squares mean ratios for area under the concentration-time curve from time 0 to infinity were reduced 37% to 55% by phosphate binders and 46% by ferrous sulfate. However, when vadadustat was administered 1 hour before phosphate binders, 90% confidence intervals for vadadustat exposure were within the no-effect boundaries of +50% to -33%, indicating that drug-drug interactions can be reduced by administering vadadustat 1 hour before phosphate binders. Vadadustat was well tolerated when administered in conjunction with phosphate binders or an iron supplement.

Iron-related parameters in dialysis patients treated with sucroferric oxyhydroxide

Background

Sucroferric oxyhydroxide is a non-calcium, iron-based phosphate binder indicated for the treatment of hyperphosphataemia in adult dialysis patients. This post hoc analysis of a randomized, 24-week Phase 3 study and its 28-week extension was performed to evaluate the long-term effect of sucroferric oxyhydroxide on iron parameters.

Methods

A total of 1059 patients were randomized to sucroferric oxyhydroxide 1.0-3.0 g/day (n = 710) or sevelamer carbonate ('sevelamer') 2.4-14.4 g/day (n = 349) for up to 52 weeks. The current analysis only included patients who completed 52 weeks of continuous treatment (n = 549). Changes in iron-related parameters and anti-anaemic product use during the study were measured.

Results

Some changes in iron-related parameters across both treatment groups were observed during the first 24 weeks of the study, and to a lesser extent with longer-term treatment. There were small, but significantly greater increases in mean transferrin saturation (TSAT) and haemoglobin levels with sucroferric oxyhydroxide versus sevelamer during the first 24 weeks (change in TSAT: +4.6% versus +0.6%, P = 0.003; change in haemoglobin: +1.6 g/L versus -1.1 g/L, P = 0.037). Mean serum ferritin concentrations also increased from Weeks 0 to 24 with sucroferric oxyhydroxide and sevelamer (+119 ng/mL and +56.2 ng/mL respectively; no statistically significant difference between groups). In both treatment groups, ferritin concentrations increased to a greater extent in the overall study population [>70% of whom received concomitant intravenous (IV) iron], compared with the subset of patients who did not receive IV iron therapy during the study. The pattern of anti-anaemic product use was similar in both treatment groups, with a trend towards higher use of IV iron and erythropoiesis-stimulating agents with sevelamer.

Conclusions

Initial increases in some iron-related parameters were observed in both treatment groups but were more pronounced with sucroferric oxyhydroxide. These differences between treatment groups with respect to changes in iron parameters are likely due to minimal iron absorption from sucroferric oxyhydroxide.

Safety and efficacy of ferric citrate in phosphate reduction and iron supplementation in patients with chronic kidney disease

Ferric citrate has been reported to have the potential to reduce phosphate and increase iron availability in patients with chronic kidney disease. In the present study, we evaluated its safety and efficacy in phosphate reduction and iron supplementation in chronic kidney disease stage 3-5 requiring dialysis patients. We systematically searched for clinical trials published in PubMed, Medline, and Cochrane databases. Only randomized controlled trials on the effects of ferric citrate in chronic kidney disease stage 3–5 requiring dialysis patients were selected. The primary outcomes were changes in serum phosphate, calcium, and anemia-related parameters. The secondary outcomes were the adverse effects of ferric citrate. Nine studies providing data on 1755 patients were included in the meta-analysis. Ferric citrate significantly reduced serum phosphate compared with placebo (mean difference, –1.39; 95% confidence interval, –2.12 to –0.66) and had a non-inferior effect compared with active treatment. Furthermore, ferric citrate significantly improved hemoglobin, transferrin saturation and ferritin. Adverse effects of constipation did not differ significantly between ferric citrate and placebo or active treatment. This review provides evidence that ferric citrate effectively alleviates hyperphosphatemia and iron deficiency in patients with chronic kidney disease stage 3–5 requiring dialysis patients. However, the included studies did not have cardiovascular complications or mortality information and could not assess whether ferric citrate affected the risk of all-cause death or cardiovascular complications in patients with chronic kidney disease. Further studies are required to assess whether the long-term use of ferric citrate can reduce the risk of cardiovascular events and all-cause mortality.