Efficacy of combined sevelamer and calcium carbonate therapy for hyperphosphatemia in Japanese hemodialysis patients.

In Japan, calcimimetics and other phosphate binders such as lantanum carbonate are not available for patients on long-term hemodialysis (HD), so we prospectively evaluated the clinical efficacy of the combination of sevelamer hydrochloride and calcium carbonate (CaCO3) for hyperphosphatemia. The study group comprised 65 HD patients who had been administered CaCO3 (>or=1500 mg/day) for hyperphosphatemia [>or=6.0 mg/dL (>or=1.94 mmol/L)]. At the beginning of the study the dose of CaCO3 was reduced by 1500 mg/day and the patients divided into two groups according to the dose of additional sevelamer hydrochloride: group A 2250 mg/day; group B 3000 mg/day. Oral active vitamin D therapy was unchanged. Fourteen patients (21.5%) dropped out because of adverse effects and of the 51 remaining patients 35 (53.8%) suffered from gastrointestinal problems. Serum phosphate concentration decreased significantly [from 7.5+/-0.8 mg/dL (2.42+/-0.26 mmol/L) to 6.6+/-1.3 mg/dL (2.13+/-0.42 mmol/L), P<0.01] in group B only after the 8 weeks of combination therapy. The calcium-phosphate product (CaxPi) also decreased in group B only [from 74.4+/-13.4 mg2/dL2 (5.99+/-1.07 mmol2/l2) to 63.7+/-15.8 mg2/dL2 (5.13+/-1.27 mmol2/l2), P<0.001]. The combination of sevelamer hydrochloride and CaCO3 is a suitable regimen for hyperphosphatemia treatment in HD patients because it avoids both the hypercalcemia of CaCO3 and the adverse effects of sevelamer hydrochloride when each is used as single-drug therapy. The ability of sevelamer hydrochloride to decrease the serum phosphate concentration is 2/3 (2250/1500 mg) that of CaCO3.