RANDOMIZED CROSSOVER STUDY COMPARING THE PHOSPHATE-BINDING EFFICACY OF CALCIUM KETOGLUTARATE VERSUS CALCIUM-CARBONATE IN PATIENTS ON CHRONIC-HEMODIALYSIS

The objective of the study was to evaluate the phosphate-binding effic acy, side effects, and cost of therapy of calcium ketoglutarate granul ate as compared with calcium carbonate tablets in patients on chronic hemodialysis. The study design used was a randomized, crossover open t rial, and the main outcome measurements were plasma ionized calcium le vels, plasma phosphate levels, plasma intact parathyroid hormone (PTH) levels, requirements for supplemental aluminum-aminoacetate therapy, patient tolerance, and cost of therapy. Nineteen patients on chronic h emodialysis were treated with a dialysate calcium concentration of 1.2 5 mmol/L and a fixed alfacalcidol dose for at least 2 months. All had previously tolerated therapy with calcium carbonate. Of the 19 patient s included, 10 completed both treatment arms. After 12 weeks of therap y, the mean (+SEM) plasma ionized calcium level was significantly lowe r in the ketoglutarate arm compared with the calcium carbonate arm (4. 8 +/- 0.1 mg/dL v 5.2 +/- 0.1 mg/dL; P = 0.004), whereas the mean plas ma phosphate (4.5 +/- 0.3 mg/dL v5.1 +/- 0.1 mg/dL) and PTH levels (26 6 +/- 125 pg/mL v 301 +/- 148 pg/mL) did not differ significantly betw een the two treatment arms. Supplemental aluminum-aminoacetate was not required during calcium ketoglutarate treatment, while two patients n eeded this supplement when treated with calcium carbonate. Five of 17 (29%) patients were withdrawn from calcium ketoglutarate therapy withi n 1 to 2 weeks due to intolerance (anorexia, vomiting, diarrhea, gener al uneasiness), whereas the remaining 12 patients did not experience:a ny side effects at all. The five patients with calcium ketoglutarate i ntolerance all had pre-existing gastrointestinal symptoms; four of the m had received treatment with cimetidine or omeprazol before inclusion into the study. Calculations based on median doses after 12 weeks sho wed that the cost of the therapy in Denmark was 10 times higher for ca lcium ketoglutarate compared with calcium carbonate (US$6.00/d v US$0. 65/d). Calcium ketoglutarate may be an effective and safe alternative to treatment with aluminum-containing phosphate binders in patients on hemodialysis who are intolerant of calcium carbonate or acetate becau se of hypercalcemia. However, care must be exercised when dealing with patients with pre-existing gastrointestinal discomfort. Due to the hi gh cost of the therapy, calcium ketoglutarate should be used only for selected patients. (C) 1998 by the National Kidney Foundation, Inc.