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Oral phosphate binders are the main stay of treatment of hyperphosphatemia. Adherence rates to ferric citrate, a recently approved phosphate binder, are unknown.We conducted a post-hoc analysis to evaluate whether adherence rates were different for ferric citrate vs. active control in 412 subjects with end stage kidney disease (ESKD) who were randomized to ferric citrate vs. active control (sevelamer carbonate and/or calcium acetate). Adherence was defined as percent of actual number of pills taken to total number of pills prescribed.There were no significant differences in baseline characteristics including gender, race/ethnicity, and age between the ferric citrate and active control groups. Baseline phosphorus, calcium, and parathyroid hormone levels were similar. Mean (SD) adherence was 81.4% (17.4) and 81.7% (15.9) in the ferric citrate and active control groups, respectively (P = 0.88). Adherence remained similar between both groups after adjusting for gender, race/ethnicity, age, cardiovascular disease (CVD), and diabetic nephropathy (mean [95% CI]: 81.4% [78.2, 84.6] and 81.5% [77.7, 85.2] for ferric citrate and active control, respectively). Gender, race/ethnicity, age, and diagnosis of diabetic nephropathy did not influence adherence to the prescribed phosphate binder. Subjects with CVD had lower adherence rates to phosphate binder; this was significant only in the active control group.Adherence rates to the phosphate binder, ferric citrate, were similar to adherence rates to active control. Similar adherence rates to ferric citrate are notable since tolerance to active control was an entry criteria and the study was open label. Gender, race/ethnicity, nor age influenced adherence.

Chronic kidney disease associated mineral and bone disorders arise as a result of aberrant bone mineral metabolism in patients with advancing levels of renal dysfunction and end-stage renal disease. One of the cornerstones of treatment is the use of phosphate-binding agents. We describe the rationale and study design for a clinical trial to assess the safety and efficacy of ferric citrate as a phosphate binder. This trial is a three-period, international, multicenter, randomized, controlled clinical trial to assess the safety and efficacy of ferric citrate as a phosphate binder, consisting of a 2-week washout period, a 52-week safety assessment period in which subjects are randomized to ferric citrate or active control, and a 4-week efficacy assessment period in which subjects randomized to ferric citrate in the safety assessment period are randomized to ferric citrate or placebo. Eligible subjects include end-stage renal disease patients who have been treated with thrice-weekly hemodialysis or peritoneal dialysis for at least 3 months in dialysis clinics in the United States and Israel. Primary outcome measure will be the effect of ferric citrate vs. placebo on the change in serum phosphorus. Safety assessments will be performed by monitoring adverse events, concomitant medication use, and sequential blood chemistries (including iron parameters, phosphorus, and calcium). This three-period trial will assess the efficacy of ferric citrate as a phosphate binder. If proven safe and efficacious, ferric citrate will likely provide an additional phosphate binder to treat chronic kidney disease associated mineral and bone disorders.