Evaluation of short-chain polypeptides as an osmotic agent in continuous ambulatory peritoneal dialysis patients

To assess whether dialysate containing short-chain polypeptides is well tolerated in continuous ambulatory peritoneal dialysis (CAPD) patients and to determine its effect on fluid and solute transport, plasma amino acid levels, and biochemical parameters.

Two-treatment, two-period cross-over design.

Renal Unit, Academic Medical Center, Amsterdam and Renal Unit, University Hospital, Gent.

Two groups of 10 stable CAPD patients.

All patients received a trial solution (1.36% glucose and 1% peptides, 381 mOsm/kg) and a control solution (2.27% glucose, 404 mOsm/kg) in randomized order. The patients were examined on four consecutive days in which two dwell periods on days 1 and 3 of either 4 (Group I) or 8 hours (Group II) were performed.

The peptide solution was well tolerated in all patients. In addition, no differences were found in the parameters for the effective peritoneal surface area and the intrinsic permeability, implying that no irritating effect of the peptide solution was present. Net ultrafiltration was not different in Group I: -43 +/- 125 versus 86 +/- 125 mL (mean +/- SEM) and marginally lower in Group II: -94 +/- 64 versus 51 +/- 64 mL, despite the lower osmolality of the trial solution compared to the control solution. Glucose absorption was higher than the peptide absorption in all patients: Group I: 66 +/- 10% versus 57 +/- 13% (p = 0.0003); Group II: 80 +/- 5% versus 72 +/- 11% (p = 0.006). No differences in plasma amino acid profiles could be detected.

Short-chain polypeptides are absorbed less than glucose and can be used as an osmotic agent in CAPD patients. However, longer-term studies are needed to evaluate possible additional effects of peptides on the nutritional status of CAPD patients.