In Vitro Stability of Insulin Aspart in Simulated Continuous Subcutaneous Insulin Infusion Using a MiniMed® 508 Insulin Pump

Abstract

This study was designed to assess the stability and potency of insulin aspart under experimental circumstances simulating worst-case conditions during clinical use for continuous subcutaneous insulin infusion (CSII). The potency and stability of two batches of U100 insulin aspart, one recently manufactured and one nearing the end of shelf life, were evaluated after storage in a Medtronic (Northridge, CA) MiniMed 508 pump for up to 7 days at 37 +/- 2 degrees C. The pumps were placed on a vibrating platform (30 +/- 3 oscillations/min, 2 +/- 0.5 cm amplitude displacement) for 24 h/day to simulate movement by the pump user. The product remaining in the pump reservoir was tested at days 3, 4, and 7 and compared with control samples. After 7 days of in-pump use, there was no significant reduction in potency of insulin aspart or difference from reference values with regards to pH, isoAsp(B28), desamido insulin aspart, insulin aspart-related impurities, or high-molecular-weight proteins. The concentration of phenol and m-cresol remained at levels sufficient to ensure preservative efficacy for both control and test samples. There was no evidence of fibrillation or precipitation. The data indicate that storage in the plastic pump reservoir under temperature and vibration conditions simulating worst-case conditions during clinical use for CSII did not affect the stability or potency of insulin aspart significantly, and support an in-pump-use time of 7 days in the MiniMed 508 pump.