Oral fluid removal by water-adsorbent polymer for end-stage renal disease

Abstract

Hypertension and accelerated vascular damage in hemodialysis patients have been ascribed to the accumulation of sodium and water before hemodialysis and their rapid extraction during the successive 4-h hemodialysis. We hypothesized that oral administration of water-adsorbing polymers might increase stool sodium and water contents and prevent overhydration. We tested the solute adsorption capacities of the water-adsorbing polymers Akuarikku CA K-4, K-25, H-2, H-3, CS-7M, and SCN-50 in artificial gastric juice. The adsorbing capacity in the artificial gastric juice was less than one-twentieth of that in water for all of the polymers except CS-7M. CS-7M also maintained its adsorbing capacity after 5h. We administered 0.2g of Akuarikku CS-7M suspended in 2ml polyethylene glycol by a metal gastric tube to 300-g Sprague-Dawley rats. The fecal weights after 5 days of administration were 9.2±0.6 g/day in the polymer group (n=5) and 7.3±0.6 g/day in control group (n=5) (P<0.01). Their dry weights were 4.2±0.2g and 3.2±0.3g/day (P<0.01), respectively. Fecal nitrogen and sodium contents were higher in the polymer group than those in the control group (P<0.01). There were no differences in potassium and phosphate contents. Oral administration of the water adsorbent to rats increased the water and nitrogen contents of feces. These observations might suggest the potential efficacy of water adsorbent as an additive for treatment of patients with severe overhydration.