Abstract
BACKGROUND AND OBJECTIVES: Lanthanum carbonate (FOSRENOL, Shire Pharmaceuticals) is an effective noncalcium, nonresin phosphate binder for the control of hyperphosphatemia in chronic kidney disease (CKD) stage 5 patients undergoing dialysis. DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS: A Phase 2, randomized, double-blind, placebo-controlled trial evaluating the efficacy and safety of lanthanum carbonate in CKD stage 3 and 4 patients. Of 281 patients screened, 121 were randomized (2:1) to lanthanum carbonate or placebo (80 versus 41). The modified intent-to-treat population included 90 patients (56 versus 34); 71 (43 versus 28) completed the study. After run-in, when any current phosphate binders were discontinued and dietary counseling reinforced, patients with serum phosphorus >4.6 mg/dl received lanthanum carbonate (titrated up to 3000 mg/d) or matching placebo for 8 wk. RESULTS: At the end of treatment, 25 (44.6%) versus nine (26.5%) patients had serum phosphorus < or =4.6 mg/dl (difference 18.1%, P = 0.12) in the lanthanum carbonate and placebo groups, respectively. Statistically significant differences were observed between groups in change from baseline to end of treatment for serum phosphorus (P = 0.02), intact parathyroid hormone (P = 0.02), and urinary phosphorus excretion (P = 0.04). The safety profile and tolerability of lanthanum carbonate were similar to that of placebo. CONCLUSIONS: Because <1% of phosphorus is in the extracellular fluid, serum measurements may not accurately reflect total body burden in patients with CKD stages 3 and 4. However, lanthanum carbonate is an effective phosphate binder in this patient population, with a safety profile and tolerability similar to that of placebo.