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.
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.


CONCLUSIONS
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.
Hospital Marques de Valdecilla, Universidad de Cantabria, Santander, Spain. angelmartindefrancisco@gmail.com
Angel L M
AL
de Francisco
Michael
M
Leidig
Adrian C
AC
Covic
Markus
M
Ketteler
Ewa
E
Benedyk-Lorens
Gabriel M
GM
Mircescu
Caecilia
C
Scholz
Pedro
P
Ponce
Jutta
J
Passlick-Deetjen
D000085:Acetates / Q000009:adverse effects / Q000627:therapeutic use*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000097:blood; D017610:Calcium Compounds / Q000009:adverse effects / Q000627:therapeutic use; D005260:Female; D006801:Humans; D054559:Hyperphosphatemia / Q000097:blood / Q000188:drug therapy*; D008274:Magnesium / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000097:blood; D011073:Polyamines / Q000627:therapeutic use*; D006435:Renal Dialysis; D000069603:Sevelamer
D000085:Acetates; D017610:Calcium Compounds; D010281:Parathyroid Hormone; D011073:Polyamines; C005479:magnesium carbonate; D010758:Phosphorus; D000069603:Sevelamer; D000469:Alkaline Phosphatase; D008274:Magnesium; C120662:calcium acetate