LAS VEGAS—Lanthanum carbonate binds dietary phosphorus more effectively than sevelamer, researchers reported here at the National Kidney Foundation’s Spring Clinical Meetings.

Researchers came to that conclusion after conducting three studies. In one study, healthy volunteers received a standard meal alone or with lanthanum carbonate (1,000 mg) or sevelamer carbonate (2,400 mg) in random order followed by a fasting period, with stool phosphorus measured 10 hours later.

In a second study, serum phosphorus was measured in dialysis patients receiving lanthanum carbonate (2,250-3,000 mg/day), then sevelamer hydrochloride (4,800-6,400 mg/day), vice versa, for four weeks each. In the third study, serum calcitriol was measured in healthy volunteers taking calcitriol (ug), and with lanthanum carbonate (3,000 mg/day) or sevelamer carbonate (7,200 mg/day) in random order.

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In the first study, the mean phosphorus absorption was 281 mg for the meal alone, 156 mg for the meal plus lanthanum carbonate, 221.8 for the meal plus sevelamer carbonate. Bound phosphorus was 135.1 mg with lanthanum carbonate and 63.2 with sevelamer carbonate. These differences between the two drugs were statistically significant.

In the second study, phosphorus reductions were 1.7 mg/dL with lanthanum carbonate and 1.4 mg/dL with sevelamer hydrochloride, a non-significant difference. Among study completers, the between-group difference was 0.5 mg/dL in favor of lanthanum carbonate. In addition, a significantly higher percentage of patients had a 25% or greater decrease in serum phosphorus with lanthanum carbonate than with sevelamer hydrochloride (51.8% vs. 38.5%).

Lastly, study 3 showed that lanthanum carbonate did not affect calcitriol exposure, whereas sevelamer carbonate treatment was associated with a significant decrease in calcitriol (137 vs. 318 pg.h/mL) and maximum serum concentration of calcitriol (40.1 vs. 49.7 pg/mL) compared with calcitriol alone.