bixalomer and Gastroesophageal-Reflux

It has been reported that sevelamer hydrochloride, which is often used as a polymer phosphorus (P) binder for managing serum P concentration in dialysis patients, causes gastrointestinal adverse effects such as constipation, etc. The reason for this is thought to be that sevelamer hydrochloride has high water absorption, causing it to absorb water and swell in the gastrointestinal tract. In June 2012, the new polymer P binder bixalomer was launched in Japan. Since bixalomer has low swelling due to water absorption, it can be expected to alleviate adverse effects in the gastrointestinal system. In our study, for 21 cases of maintenance hemodialysis patients undergoing treatment with sevelamer hydrochloride at our hospital, the P binder was switched from sevelamer hydrochloride to the same dosage of bixalomer, and the concentrations of serum P, corrected calcium (Ca) and whole parathyroid hormone (PTH) before and one month after the switch were compared. In addition, gastrointestinal symptoms (acid reflux, abdominal pain, indigestion, diarrhea and constipation) were evaluated before and after the switch using a questionnaire based on the Japanese version of the Gastrointestinal Symptom Rating Scale (GSRS). By switching to bixalomer, serum P concentration was significantly reduced (P=0.024), but there were no significant changes observed for serum corrected Ca and whole PTH. Furthermore, there were no significant changes observed for all five of the evaluation items of the GSRS, before and after the switch. These results suggest that although bixalomer can more potently reduce the serum P concentration than sevelamer hydrochloride, there were no significant differences in the effects of both P binders on the gastrointestinal symptoms.

Topics: Abdominal Pain; Aged; Calcium; Chelating Agents; Constipation; Diarrhea; Dyspepsia; Female; Gastroesophageal Reflux; Gastrointestinal Diseases; Humans; Hyperphosphatemia; Japan; Kidney Failure, Chronic; Male; Parathyroid Hormone; Phosphorus; Polyamines; Renal Dialysis; Sevelamer; Surveys and Questionnaires

Bixalomer (Bix) is an amine-functional polymer, non-calcium-containing phosphate (P) binder, and has been clinically available in Japan recently. Bix is expected to cause fewer gastrointestinal (GI) side-effects as compared with sevelamer hydrochloride (SH), because of less expansion of Bix in the GI tract. In this prospective observational study, we evaluated changes in GI symptoms by the Gastrointestinal Symptom Rating Scale (GSRS) score in long-term hemodialysis (HD) outpatients with SH-associated GI symptoms who switched to Bix from SH. A total of 114 patients (age 63.7±10.8 year (mean±SD), female 65.5%, HD vintage 11.2±8.6 years, diabetes mellitus 27.4%) were enrolled. The GSRS score was checked at 0 and 12 weeks after the start of Bix. Bix was started at the initial dose of 750 mg/day, and then was titrated. Serum albumin, P and corrected calcium levels did not significantly change during Bix treatment. However, serum low-density lipoprotein-cholesterol and bicarbonate levels significantly increased during Bix treatment (P<0.001). In GSRS scores, total and domain-specific scores, including constipation, diarrhea, reflux and abdominal pain were significantly reduced at 0, 4, 12 and 24 weeks as compared with those at 0 weeks (P<0.05). This study shows that Bix was well tolerated and managed hyperphosphatemia effectively after switching from SH in Japanese patients on long-term HD. In addition, Bix might be less often associated with GI symptoms as compared with SH.

Topics: Abdominal Pain; Bicarbonates; Calcium; Chelating Agents; Cohort Studies; Constipation; Female; Follow-Up Studies; Gastroesophageal Reflux; Gastrointestinal Diseases; Humans; Hyperphosphatemia; Japan; Kidney Failure, Chronic; Lipids; Male; Middle Aged; Phosphates; Phosphorus; Polyamines; Prospective Studies; Renal Dialysis