Dp. Rosenbaum et al., EFFECT OF RENAGEL(R), A NONABSORBABLE, CROSS-LINKED, POLYMERIC PHOSPHATE BINDER, ON URINARY PHOSPHORUS EXCRETION IN RATS, Nephrology, dialysis, transplantation, 12(5), 1997, pp. 961-964
Background. Normalization of serum phosphorus is critical in the treat
ment of End Stage Renal Failure patients. Aluminum or calcium based ph
osphate binders, while efficacious, are associated with potential adve
rse side effects and toxicities. We have developed RenaGel(R), a novel
, non-absorbed hydrogel which binds dietary phosphate leading to incre
ased fecal excretion, decreased absorption and decreased serum phospho
rus levels. In this paper, we present results from both in vitro and i
n vivo studies in which we examined the efficacy of this novel phospha
te binder. Methods. In vitro, RenaGel(R) was suspended in the test sol
ution, and the mixture was stirred for 1 hour at room temperature. The
solid was then filtered off, and the residual liquid analyzed for pho
sphate. In vivo, RenaGel was mixed in rodent feed at different concent
rations and fed to normal rats for up to 4 days. Urine was collected a
nd analysed for phosphate content. Results and conclusions. In vitro b
inding studies demonstrate that RenaGel has an extremely high phosphat
e binding capacity. At an estimated physiological concentration of 5 m
M phosphate, RenaGel binds 2.6 mmole phosphate/g of phosphate binder.
The in vivo binding study shows that RenaGel mixed into the diet decre
ased urinary phosphorus excretion in a dose dependent manner. RenaGel
particles with a 23 mu m mean diameter are more efficacious than the l
arger ones. In conclusion, the above studies indicate that RenaGel is
a potent phosphate binder. RenaGel(R) contains no calcium or aluminum
and offers an alternative to existing phosphate binder treatments.