Efficacy and tolerance of three different calcium acetate formulations in hemodialysis patients

Calcium acetate (CaAc) is an effective phosphate binder in patients with chronic renal failure. However, an important side effect is gastro-intestinal discomfort. Phos-ex (Cablon, The Netherlands) is the only commercially available non-coated CaAc formulation in our country. We developed two new CaAc formulations: neutral-coated CaAc (NCCaAc) and enteric-coated CaAc (ECCaAc).

In a randomised double-blinded cross-over trial we compared efficacy and tolerance of the three formulations in 19 stable hemodialysis patients, with a mean age of 63 years (range, 36-85), who had been on hemodialysis for 19 months (range, 6-47). Patients were randomised to receive NCCaAc or ECCaAc, with meals, for a period of 10 weeks and after cross-over for another 10 weeks. During a third non-blinded period, patients received Phos-ex for 10 weeks.

Serum phosphate was significantly higher with ECCaAc compared to NCCaAc (1.89 +/- 0.07 vs. 1.70 +/- 0.08 mmol/l, P < 0.05). Serum Ca was significantly lower with ECCaAc compared to NCCaAc or Phos-ex (2.38 +/- 0.04, 2.47 +/- 0.04 and 2.48 +/- 0.04 mmol/l, P < 0.05). There were less hypercalcemic and more hyperphosphatemic events in the ECCaAc period, compared to the other periods. The daily CaAc dose and dietary intake of calcium, phosphate, protein and calories were comparable in all three periods. With Phos-ex, patients noticed more gastro-intestinal complaints than with to NCCaAc and ECCaAc. Two patients stopped taking Phos-ex because of side effects.

In hemodialysis patients, phosphate control and tolerance were both influenced by the formulation of CaAc. Although phosphate control was adequate with all three formulations of CaAc, ECCaAc was less effective compared to NCCaAc or Phos-ex. NCCaAc and ECCaAc were better tolerated than Phos-ex. Regarding efficacy and tolerance, NCCaAc was the best calcium acetate formulation.