Dose-finding study of bixalomer in patients with chronic kidney disease on hemodialysis with hyperphosphatemia: a double-blind, randomized, placebo-controlled and sevelamer hydrochloride-controlled open-label, parallel group study.

Hyperphosphatemia is a prognostic factor for morbidity and mortality in chronic kidney disease. Bixalomer (Kiklin® Capsules) is a non-absorbable polymer that decreases serum phosphate levels by binding phosphate in the gastrointestinal tract. This study was a multicenter, double-blind, randomized, placebo-controlled study to confirm the superiority of bixalomer to placebo for a 4-week treatment period in patients with chronic kidney disease on hemodialysis with hyperphosphatemia. Sevelamer hydrochloride (HCl), a similar non-absorbable polymer, was used as an active comparator for open-label as a reference without statistical comparison for efficacy and safety. The primary endpoint was the change in serum phosphorus level from baseline. The safety profile was also investigated. The number of subjects was 32 in the placebo group and 31 in each bixalomer group (1.5, 3.0 and 4.5 g/day), respectively. The baseline serum phosphorus level was 7.95 to 8.25 mg/dL. Bixalomer showed a significant decrease in serum phosphorus level at all doses compared with placebo, and the adjusted mean change in serum phosphorus level from the baseline to the end of treatment (at Week 4 or at the time of discontinuation) was +0.24 mg/dL in the placebo group, -0.75 mg/dL in the 1.5 g/day group, -1.32 mg/dL in the 3.0 g/day group, and -1.80 mg/dL in the 4.5 g/day group, showing a dose-dependent decrease in serum phosphorus level. The mean change in serum phosphorus level was -2.32 mg/dL in the sevelamer HCl group under the mean dose of 4.8 g/day. Major adverse events included constipation, hard feces, vomiting, etc.; however, none of the adverse events were serious or severe. Consequently, the superiority of bixalomer to placebo and its dose-dependency for treating hyperphosphatemia were confirmed (Clinical trial registration: NCT00505037).