Ranitidine reduces phosphate binding in dialysis patients receiving calcium carbonate

BACKGROUND: In a previous controlled study we showed that ranitidine significantlyreduced the phosphate binding of aluminium hydroxide in patientswith renal failure, probably by increasing intragastric pH. METHODS: In this study we have investigated the effect of ranitidineon the phosphate binding of calcium carbonate in fifteen dialysispatients. Ranitidine 300 mg or a placebo tablet was taken beforebreakfast for two 4-week periods in a double-blind crossovertrial with no washout period. The mean daily dose of calciumcarbonate was 2 g and neither the dose nor the patient's dietwas changed during the study period. Blood was taken at 2-weeklyintervals for serum phosphate, calcium, albumin, and alkalinephosphatase measurements, and at the end of each treatment periodfor parathyroid hormone (PTH) level. RESULTS: Serum phosphate concentrations were significantly higher duringthe ranitidine than the placebo phase, 1.78 (±0.43 SD)versus 1.59 (±0.49 SD) mmol/1 (P<0.001). Serum calcium,albumin, PTH, and alkaline phosphatase concentrations did notdiffer between the two treatment periods. CONCLUSION: This study shows that ranitidine has a significant adverse effecton the phosphate binding of calcium carbonate in patients withrenal failure.