Enhancement of Clearances by Activated Charcoal in an in Vitro Model of Peritoneal Dialysis

Abstract

The use of sorbents in dialysate to increase solute clearances in continuous ambulatory peritoneal dialysis (CAPD) was investigated. With in vitro simulations of CAPD, the kinetics of irreversible binding of creatinine to activated charcoal were assessed. Cellulose dialyzer fibers were submerged in two liters of dialysate for 3-8 hour exchanges. Perfusate was pumped single pass through the fibers. Commercial dialy-sates with 1.5%. and 4.25% dextrose as an osmotic agent were controls. Experimental exchanges contained either large or small particles of activated charcoal. Unencapsulated and collodion encapsulated large particles were also studied. From the perfusate side, creatinine, clearance and mass transfer were determined; dialysate/perfusate ratios (D/P) of free creatinine concentrations were assessed. We found that incorporation of small unencapsulated particles of activated charcoal would double both clearance and mass transfer of creatinine. It also maintained D/P values less than 0.6 even up to 8 hours. Small particles absorbed more than 10 times more creatinine per gram than large particles. Significant differences between encapsulated and unencapsulated large particles were not found. In summary, activated charcoal might double creatinine removal per exchange in CAPD. Animal studies of collodion encapsulated small particles and other sorbent-enzyme systems in CAPD dialysate solutions seem warranted.