RANITIDINE REDUCES PHOSPHATE-BINDING IN DIALYSIS PATIENTS RECEIVING CALCIUM-CARBONATE

Background. In a previous controlled study we showed that ranitidine s ignificantly reduced the phosphate binding of aluminium hydroxide in p atients with renal failure, probably by increasing intragastric pH. Me thods. In this study we have investigated the effect of ranitidine on the phosphate binding of calcium carbonate in fifteen dialysis patient s. Ranitidine 300 mg or a placebo tablet was taken before breakfast fo r two 4-week periods in a double-blind crossover trial with no washout period. The mean daily dose of calcium carbonate was 2 g and neither the dose nor the patient's diet was changed during the study period. B lood was taken at 2-weekly intervals for serum phosphate, calcium, alb umin, and alkaline phosphatase measurements, and at the end of each tr eatment period for parathyroid hormone (PTH) level. Results. Serum pho sphate concentrations were significantly higher during the ranitidine than the placebo phase, 1.78 (+/- 0.43 SD) versus 1.59 (+/- 0.49 SD) m mol/l (P<0.001). Serum calcium, albumin, PTH, and alkaline phosphatase concentrations did not differ between the two treatment periods. Conc lusion. This study shows that ranitidine has a significant adverse eff ect on the phosphate binding of calcium carbonate in patients with ren al failure.