Evaluation of calcium acetate/magnesium carbonate as a phosphate binder compared with sevelamer hydrochloride in haemodialysis patients: a controlled randomized study (CALMAG study) assessing efficacy and tolerability

Nephrol Dial Transplant. 2010 Nov;25(11):3707-17. doi: 10.1093/ndt/gfq292. Epub 2010 Jun 7.


Background: Phosphate binders are required to control serum phosphorus in dialysis patients. A phosphate binder combining calcium and magnesium offers an interesting therapeutic option.

Methods: This controlled randomized, investigator-masked, multicentre trial investigated the effect of calcium acetate/magnesium carbonate (CaMg) on serum phosphorus levels compared with sevelamer hydrochloride (HCl). The study aim was to show non-inferiority of CaMg in lowering serum phosphorus levels into Kidney Disease Outcome Quality Initiative (K/DOQI) target level range after 24 weeks. Three hundred and twenty-six patients from five European countries were included. After a phosphate binder washout period, 255 patients were randomized in a 1:1 fashion. Two hundred and four patients completed the study per protocol (CaMg, N = 105; dropouts N = 18; sevelamer-HCl, N = 99; dropouts N = 34). Patient baseline characteristics were similar in both groups.

Results: Serum phosphorus levels had decreased significantly with both drugs at week 25, and the study hypothesis of CaMg not being inferior to sevelamer-HCl was confirmed. The area under the curve for serum phosphorus (P = 0.0042) and the number of visits above K/DOQI (≤1.78 mmol/L, P = 0.0198) and Kidney disease: Improving global outcomes (KDIGO) targets (≤1.45 mmol/L, P = 0.0067) were significantly lower with CaMg. Ionized serum calcium did not differ between groups; total serum calcium increased in the CaMg group (treatment difference 0.0477 mmol/L; P = 0.0032) but was not associated with a higher risk of hypercalcaemia. An asymptomatic increase in serum magnesium occurred in CaMg-treated patients (treatment difference 0.2597 mmol/L, P < 0.0001). There was no difference in the number of patients with adverse events.

Conclusion: CaMg was non-inferior to the comparator at controlling serum phosphorus levels at Week 25. There was no change in ionized calcium; there was minimal increase in total serum calcium and a small increase in serum magnesium. It had a good tolerability profile and thus may represent an effective treatment of hyperphosphataemia.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / adverse effects
  • Acetates / therapeutic use*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Alkaline Phosphatase / blood
  • Calcium Compounds / adverse effects
  • Calcium Compounds / therapeutic use
  • Female
  • Humans
  • Hyperphosphatemia / blood
  • Hyperphosphatemia / drug therapy*
  • Magnesium / adverse effects
  • Magnesium / therapeutic use*
  • Male
  • Middle Aged
  • Parathyroid Hormone / blood
  • Phosphorus / blood
  • Polyamines / therapeutic use*
  • Renal Dialysis*
  • Sevelamer


  • Acetates
  • Calcium Compounds
  • Parathyroid Hormone
  • Polyamines
  • magnesium carbonate
  • Phosphorus
  • Sevelamer
  • Alkaline Phosphatase
  • Magnesium
  • calcium acetate