Lispro Insulin: Adsorption and Stability in Selected Intravenous Devices

PURPOSE The adsorption characteristics and stability profile of an insulin analog, lispro insulin, were evaluated against a recombinant human regular insulin using intravenous infusion sets and syringes. METHODS Studies were performed using either 0.9% NaCl or 5% dextrose intravenous injection solution. Effects of container type, infusion rate, product concentration, presence/absence of an in-line filter, and storage condition on release profiles of lispro and human regular insulin infusion solutions were determined. RESULTS Lispro insulin and m-cresol were chemically stable. Release rates of insulin (both types) were steady after an initial lag time. The lag time was much longer with intravenous bag infusion than with intravenous syringe infusion. A higher product concentration, faster flow rate, and prewash of the infusion tubing were shown to substantially decrease the lag time. CONCLUSIONS The adsorption profile of lispro insulin was the same as that of human regular insulin in both syringes and bags. Use of a load-and-sit prewash scheme may shorten or nearly eliminate the lag time, which in turn may be used to make a more accurate calculation of a patient's dose.