EFFECT OF RENAGEL(R), A NONABSORBED, CALCIUM-FREE AND ALUMINUM-FREE PHOSPHATE BINDER, ON SERUM PHOSPHORUS, CALCIUM, AND INTACT PARATHYROID-HORMONE IN END-STAGE RENAL-DISEASE PATIENTS

Background. Control of dietary phosphate absorption in end-stage renal disease patients is essential to prevent the deleterious sequelae of phosphorus retention. Efficacy of currently available calcium- and alu minium-containing phosphate binders is constrained by the side-effects associated with the absorption of calcium and aluminium. The current study examined the efficacy of RenaGel, a calcium- and aluminium-free, polymeric phosphate binder, in end-stage renal disease patients. Meth ods. Administration of calcium- or aluminium-containing phosphate bind ers ceased during a 2-week washout period. RenaGel, at starting doses of one, two, or three 500-mg capsules three times per day with meals, was administered for 8 weeks. RenaGel dose was titrated up 1 capsule p er meal at the end of each 2-week period if necessary to achieve phosp horus control. A second 2-week washout period followed the end of Rena Gel treatment. Results. Mean serum phosphorus rose from a pre-washout level of 6.9 mg/dl (2.23 mmol/l) to 8.1 mg/dl (2.62 mmol/l) at the end of the initial 2-week washout. With RenaGel treatment, serum phosphor us declined and returned to pre-washout levels after 4 weeks. Serum ph osphorus reached a nadir of 6.5 mg/dl (2.10 mmol/l) after 7 weeks of R enaGel treatment. Serum phosphorus rose to 8.2 mg/dl (2.65 mmol/l) 2 w eeks after cessation of RenaGel treatment. As anticipated, calcium dec lined during the initial washout period when calcium-based phosphate b inders were stopped for the majority of patients. The rise in serum ph osphorus and decline in serum calcium during washout resulted in an in crease in median intact parathyroid hormone (iPTH) levels from 292 pg/ ml to 395 pg/ml. iPTH fell to 283 pg/ml after 6 weeks of RenaGel treat ment despite a persistently lower serum calcium. RenaGel treatment als o reduced serum total and LDL cholesterol by 25 mg/dl (0.65 mmol/l) an d 23 mg/dl (0.59 mmol/l) respectively. Conclusions. RenaGel appears to be an effective phosphate binder free of calcium and aluminium. Phosp horus control with two to four RenaGel capsules per meal appears to re sult in comparable phosphorus lowering seen with calcium- or aluminium -based phosphate binders. RenaGel may offer an alternative for the con trol of phosphorus retention in end-stage renal disease patients.