Availability of insulin from parenteral nutrient solutions.

The effect of the following variables on insulin loss from total parenteral nutrient solutions was examined: (1) time of infusion sample; (2) insulin concentration; (3) amino acid or polypeptide source; (4) electrolytes and vitamins; (5) inline filters; (6) glass and polyvinyl chloride (PVC) infusion containers; and (7) human albumin. I125-tagged insulin was added to various parenteral nutrient solutions in liter containers. These solutions were prepared and drained to simulate actual clinical use. The drained solutions were collected and measured for radioactivity, and the percent of insulin remaining in the infusion container was calculated. Basic solutions of amino acids and protein hydrolysates in dextrose with 30 units of insulin failed to deliver approximately 44 to 47% of the added insulin. Varying the concentration of insulin had a small but statistically significant effect on the degree of insulin loss. The use of inline filters and PVC bags caused an even greater loss of insulin. The addition of albumin or electrolytes and vitamins decreased the insulin loss.