Binding of insulin to a continuous ambulatory peritoneal dialysis system

The binding of insulin in two peritoneal dialysis solutions to polyvinyl chloride dialysate containers and an administration set and the effect of adding antibiotics to the dialysate solutions were studied in a simulated continuous ambulatory peritoneal dialysis (CAPD) system. Using a radiotracer method, binding of insulin to dialysate containers was determined at various times up to 48 hours after addition of 10, 20, 40, and 80 units of insulin each to 2 L of either 1.5% or 4.25% dextrose dialysate solution. The method was repeated in 1-L glass containers. Each of the dialysate solutions was then passed through a CAPD administration set to determine binding to the set's cellulose-ester membrane filter. In another experiment to simulate binding to the set in actual practice, three bags of 1.5% dextrose dialysate were alternately infused with one bag of 4.25% dextrose dialysate through a single CAPD set until eight bags of dialysate containing insulin 40 units were given over 48 hours. The ability of gentamicin sulfate and cephalothin sodium to release bound insulin from the CAPD filter was determined by passing 2 L of each dialysate solution containing either gentamicin 60 mg or cephalothin 500 mg through the set over an 18-minute period. The binding of these antibiotics to the dialysate bags was also studied using high-performance liquid chromatography assays. Insulin binding to the bag increased with increasing insulin concentration and length of storage in the bag; binding was not significantly different between the two dialysate solutions except at the 80-unit/2-L concentration. Binding in glass containers was less than that in polyvinyl chloride bags.(ABSTRACT TRUNCATED AT 250 WORDS)