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.