Effects of antacids on the phosphate‒lowering efficacy of lanthanum carbonate and sucroferric oxyhydroxide： a retrospective study

Abstract

The treatment of hyperphosphatemia is one of the most important therapeutic strategies for chronic kidney disease‒mineral and bone disorder. The oral administration of phosphate binders is essential for achieving both adequate protein intake and efficient improvement of hyperphosphatemia. This study aimed to clarify the phosphate‒lowering effects of lanthanum carbonate and sucroferric oxyhydroxide and how they are influenced by oral antacids, such as proton‒pump inhibitors. We surveyed 163 maintenance hemodialysis patients who were started on either of the abovementioned phosphate binders or had their doses of these drugs increased at one of our facilities between April 2017 and December 2019. The patients’ background characteristics and the changes in their serum phosphate concentrations seen at 4 weeks after drug changes were investigated. Patients who were switched from other phosphate binders or had their dialysis conditions or doses of vitamin D drugs or calcimimetics changed during the observation period were excluded. In the sucroferric oxyhydroxide group, the discontinuation of oral administration due to adverse effects was significantly more common； however, the reduction in the serum phosphate concentration per 250 mg dose was significantly larger than that seen in the lanthanum carbonate group (0.94±0.79 mg/dL vs. 0.51±0.43 mg/dL, p＜0.01). Regarding the effects of antacids, in the lanthanum carbonate group, the reduction in the serum phosphate concentration per 250 mg dose was significantly smaller in the patients taking antacids (0.44±0.45 mg/dL vs. 0.67±0.33 mg/dL, p＜0.01), whereas no such difference was observed in the sucroferric oxyhydroxide group (0.98±0.77 mg/dL vs. 0.86±0.87 mg/dL, p＝0.70). This suggests that the phosphate‒lowering effect of lanthanum carbonate is attenuated by the increase in gastric pH induced by antacids, while the effect of sucroferric oxyhydroxide remains stable under high pH conditions. Great care is required during the selection of phosphate binders and the interpretation of blood test results in patients taking antacids.