Instability of Insulin Aspart Diluted in Dextrose

Abstract

Insulin aspart (Novorapid) is a rapid-acting insulin analog that is maintained in hexameric form by phenolic preservatives (phenol and metacresol) and stabilized by insulin-zinc complex. According to the manufacturers, insulin can be independently diluted either in 5% dextrose solution (D5%) or 0.9% sodium chloride solution. In reality, in most clinical units, such as the neonatal intensive care unit (NICU), insulin aspart is more frequently diluted in D5% than in saline solution due to sodium restriction. However, injectable dextrose solutions contain glucose degradation products (1) that are capable of binding proteins—like insulin—through a glycation phenomenon. Therefore, dilution of Novorapid in D5% would be more likely to cause glycated insulin and may raise a worrisome problem in terms of insulin stability. The objective of this study was to investigate the stability of insulin aspart diluted in D5% at both adult and neonate therapeutic concentrations in order to ensure its appropriateness in the preparation of insulin aspart. To address this issue, insulin aspart diluted in D5% was assayed by a stability-indicating method using high-performance liquid chromatography (HPLC) coupled with an ultraviolet (UV) detector. The nature of the formed product was determined by HPLC coupled with a mass spectrometer. The effect of …