In vitro stability of insulin aspart in simulated continuous subcutaneous insulin infusion using a MiniMed 508 insulin pump

Abstract

Background: 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).

Methods: 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.

Results: 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.

Conclusions: 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.