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Market Report: Hyperphosphatemia Drug Auryxia Is Slow to Catch On

Clinicians’ unfamiliarity with product blocks adoption

A new survey conducted by the market research company Spherix indicates that familiarity with the hyperphosphatemia treatment Auryxia (ferric citrate, Keryx Biopharmaceuticals) remains low. Market access also appears to be a barrier, which is not only hindering new patient starts, but also triggering discontinuations of Auryxia therapy. That barrier may soon be alleviated, however, based on a recent announcement from Keryx about expanded reimbursement earlier this month, the report states.

Auryxia is a phosphate binder approved in 2014 for the control of serum phosphorus levels in patients with chronic kidney disease (CKD) undergoing dialysis. Each tablet contains 210 mg of ferric iron, equivalent to 1 g of ferric citrate. Ferric iron binds dietary phosphate in the gastrointestinal (GI) tract and precipitates as ferric phosphate. This compound is insoluble and is excreted in the stool. By binding phosphate in the GI tract and decreasing absorption, ferric citrate lowers the phosphate concentration in the serum.

The survey, completed by 94 nephrologists in early July, also indicates that the anemia market is becoming more dynamic with the introduction of Mircera (methoxy polyethylene glycol-epoetin beta, Galenica), a long-acting erythropoietin-stimulating agent (ESA). Mircera is indicated for the treatment of anemia associated with CKD in adults on dialysis and not on dialysis. More than one-third of the respondents indicated that their primary dialysis units had undergone formulary changes affecting ESAs that were almost entirely in favor of Mircera.

Within the iron market, Rockwell Medical is aiming to secure a position for its iron dialysate product Triferic (ferric pyrophosphate citrate), according to the report. The product was approved in 2014 for the replacement of iron to maintain hemoglobin in adult patients with hemodialysis-dependent CKD. Surveyed nephrologists were still largely unaware of Triferic, and even among those who were somewhat familiar with the treatment, few indicated plans to incorporate it into their dialysis-center formularies.

The survey also highlights clinicians’ growing familiarity with Patiromer (Relypsa) and ZS-9 (ZS Pharma), two agents currently under FDA review for the treatment of hyperkalemia. Patiromer, a nonabsorbed, potassium-binding polymer, has been evaluated in patients with hyperkalemia, including a phase III program, a 12-month phase II trial, and a 48-hour phase I onset-of-action study. ZS-9 is an insoluble, nonabsorbed zirconium silicate designed to trap potassium ions in order to lower and maintain control of serum potassium levels. The treatment has been studied in three double-blind, placebo-controlled trials and in two ongoing 12-month, open-label studies in more than 1,600 patients with hyperkalemia.

Although most of the survey respondents who were familiar with these two products felt that it was too early to form an opinion regarding whether one holds a competitive advantage over the other, the market is clearly excited to have new options for hyperkalemia, with a fair percentage of respondents indicating that they would incorporate these new agents into their clinical practice soon after approval, the report notes.

Sources: Spherix; August 20, 2015; Auryxia Prescribing Information; July 2015; Mircera PI; October 2014; Triferic PI; June 2014; Relypsa; 2015; and ZS Pharma; July 29, 2015.

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