Adsorption of insulin by infusion materials

Doubt about insulin adsorption has been an obstacle to rational insulin treatment by i.v. infusion. The influence of several factors on adsorption was therefore studied using a radioimmunoassay technique to determine insulin levels. When 8 to 128 IU of insulin were added to 500- and 1,000-ml containers, a linear relationship was found between the amount added and the amount delivered to the patient, permitting the design of a practical nomogram. In other experiments, 32 IU of insulin was added to 1,000 ml containers. The type of insulin did not influence adsorption. Half of the 32 IU added to soda-glass and siliconized bottles were adsorbed, while plastic containers adsorbed less. Neither the type of infusion solution (except for 60% glucose), nor the type of infusion set infuenced adsorption. Human serum albumin prevented adsorption only incompletely.