Effect of pretreatment with 0.9% sodium chloride or insulin solutions on the delivery of insulin from an infusion system.

The effect of pretreating a polyvinyl chloride i.v. administration system with sodium chloride or insulin solution on the delivery of insulin was studied. Insulin labeled with iodine 125 was added to human insulin, which was added to 0.9% sodium chloride injection packaged in flexible polyvinyl chloride containers and to 0.9% sodium chloride injection placed in empty ethylene vinyl acetate containers. Samples were tested for insulin content by gamma spectrometry after storage in the bags and after infusion through four different polyvinyl chloride administration sets at different flow rates. Effluent samples were collected at 10 times (6-50 minutes) after the start of the infusion. The 0.9% sodium chloride injection had a conditioning effect on the polyvinyl chloride administration sets, indicating an electrostatic sorption mechanism for insulin. Sorption to the untreated polyvinyl chloride sets and the ethylene vinyl acetate bags was substantial and followed a Langmuir adsorption isotherm. Insulin sorption to the untreated administration sets was greatest from the first 100 mL of effluent and did not differ by flow rate or type of set investigated. Storing the sodium chloride injection in the tubing for one hour or flushing the tubing with 100 mL of sodium chloride injection or 100 mL of the insulin admixture decreased sorption by half. Storing the insulin admixture in the tubing for 30 minutes caused sorption to be reduced by a factor of three. When either of the solutions was stored in the set and then the set was flushed with the solution, sorption was even further suppressed.(ABSTRACT TRUNCATED AT 250 WORDS)