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Open Access Highly Accessed Research article

A randomized, double-blind, placebo-controlled trial of calcium acetate on serum phosphorus concentrations in patients with advanced non-dialysis-dependent chronic kidney disease

Wajeh Qunibi1*, Wolfgang C Winkelmayer2, Richard Solomon3, Moustafa Moustafa4, Paul Kessler5, Chiang-Hong Ho6, Jonathan Greenberg7 and Jose A Diaz-Buxo6

Author Affiliations

1 Department of Medicine, University of Texas Health Sciences Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA

2 Division of Nephrology, Department of Medicine, Stanford University School of Medicine, 780 Welch Road, Suite 106, Palo Alto, CA 94304, USA

3 Department of Medicine, 2308 Rehab 2, UHC Campus Fletcher Allen Health Care, University of Vermont, Burlington, VT, 05401, US

4 South Carolina Nephrology and Hypertension, 1184 Orangeburg Mall Circle, Orangeburg, SC 29115-3439, USA

5 Clinical, Medical and Regulatory Affairs, Nabi Biopharmaceuticals, 12276 Wilkins Avenue, Rockville, MD, 20852, USA

6 Renal Therapies Group, Fresenius Medical Care, 309 East Morehead Street, Suite 285, Charlotte, NC, 28202, USA

7 Daiichi Sanky, 399 Thornall Street, Edison, New Jersey 08837, USA

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BMC Nephrology 2011, 12:9  doi:10.1186/1471-2369-12-9

Published: 16 February 2011

Abstract

Background

Hyperphosphatemia in patients with chronic kidney disease (CKD) contributes to secondary hyperparathyroidism, soft tissue calcification, and increased mortality risk. This trial was conducted to examine the efficacy and safety of calcium acetate in controlling serum phosphorus in pre-dialysis patients with CKD.

Methods

In this randomized, double-blind, placebo-controlled trial, 110 nondialyzed patients from 34 sites with estimated GFR < 30 mL/min/1.73 m2 and serum phosphorus > 4.5 mg/dL were randomized to calcium acetate or placebo for 12 weeks. The dose of study drugs was titrated to achieve target serum phosphorus of 2.7-4.5 mg/dL. Serum phosphorus, calcium, iPTH, bicarbonate and serum albumin were measured at baseline and every 2 weeks for the 12 week study period. The primary efficacy endpoint was serum phosphorus at 12 weeks. Secondary endpoints were to measure serum calcium and intact parathyroid hormone (iPTH) levels.

Results

At 12 weeks, serum phosphorus concentration was significantly lower in the calcium acetate group compared to the placebo group (4.4 ± 1.2 mg/dL vs. 5.1 ± 1.4 mg/dL; p = 0.04). The albumin-adjusted serum calcium concentration was significantly higher (9.5 ± 0.8 vs. 8.8 ± 0.8; p < 0.001) and iPTH was significantly lower in the calcium acetate group compared to placebo (150 ± 157 vs. 351 ± 292 pg/mL respectively; p < 0.001). At 12 weeks, the proportions of subjects who had hypocalcemia were 5.4% and 19.5% for the calcium acetate and the placebo groups, respectively, while the proportions of those with hypercalcemia were 13.5% and 0%, respectively. Adverse events did not differ between the treatment groups.

Conclusions

In CKD patients not yet on dialysis, calcium acetate was effective in reducing serum phosphorus and iPTH over a 12 week period.

Trial Registration

www.clinicaltrials.gov NCT00211978.