RnaGel(R), a novel calcium- and aluminium-free phosphate binder, inhibits phosphate absorption in normal volunteers

Background: Available phosphate binders containaluminium or calcium which can be associated with undesirable effects.RenaGel®, cross-linked poly(allyl-amine hydrochloride) is anon-absorbed phosphate binding polymer, free of calcium and aluminium. Weconducted this study to examine the safety and phosphate binding efficacyof RenaGel in volunteers. Method: During 18 days (days0-17) at the clinical study unit, 24 subjects consumed aphosphate-controlled diet designed to provide 37.5 mmol (1200 mg) elementalphosphorus per day. From the morning of day 5 to the morning of day 9,urine and faeces were collected. Average base line urine and faecalphosphorus contents were determined. On days 9-16, the subjects receivedeither RenaGel 1 g, 2.5 g, or 5 g or placebo three times per dayimmediately prior to the meals. From the morning of day 13 to the morningof day 17, urine and faeces were again collected and phosphorus contents ontreatment were determined. Results: RenaGel inhibiteddietary phosphate absorption as measured by a decline in average dailyurinary phosphorus excretion and an increase in average daily fecalphosphorus excretion. Average urine phosphorus contents on treatment were2.7.2 mmol (870 mg) per day in the placebo group vs 23.8 mmol (762 mg),19.5 mmol (625 mg), and 16.6 mmol (530 mg) per day in the renaGel 1-g,2.5-g, and 5-g groups. Average daily faecal phosphorus content on treatmentwas markedly higher in the RenaGel 5-g group, 19.1 mmol (611 mg) per day vs10.7 mmol (342 mg) per day for the placebo group. RenaGel also decreasedtotal serum cholesterol by 0.71 mmol/L (27.5 mg/dl), 0.55mmol/l (21.3mg/dl), and 1.08 mmol/l (41.8 mg/dl for the RenaGel 1-g,and 5-g groups.RenaGel was well tolerated with adverse events similar to placebo.Conclusion: RenaGel is a safe, effective, and welltolerated phosphate binder in normal volunteers. The degree of phosphatebinding is consistent with its potential use as a phosphate binder in renalfailure patients.