Stress stability testing of Insulin Injection: A new perspective on enhancing diabetes management

Abstract

Introduction: Recommended storage for insulin injection (unopened containers) is as “Store in a refrigerator
(36°F–46°F [2°C–8°C]), but not in the freezer. Do not use if it has been frozen. If stored at room temperature, below
86°F (30°C) the vial must be discarded after 31 days. Strict storage recommendations for insulin are difficult to
follow in hot tropical regions and even more challenging in conflict and humanitarian emergency settings, adding
an extra burden to the management of people with diabetes. Objectives: According to pharmacopeia, unopened
insulin vials must be stored in a refrigerator (2°C–8°C), while storage at ambient temperature (25°C–30°C)
is usually permitted for the 4-week usage period during treatment. In the present work, we address a critical
question toward improving diabetes care in resource poor settings, namely, whether insulin is stable and retains
biological activity in tropical temperatures during a 4-week treatment period. To answer this question, we studied
temperatures in tropical conditions in various regions such as Rajasthan, parts of Gujarat and Haryana in India.
Oscillating temperatures between 25°C and 37°C were observed in various regions. Experimental: Insulin heat
stability was assessed under these specific temperatures which were precisely reproduced in the laboratory using
simulating storage chambers at 50°C, 40°C, 30°C, 25°C, and as a control 2°C–8°C. The stability of commercially
available formulations of insulin was confirmed across the assessment period (4 weeks) as it exhibited flawless
adherence to pharmacopeial guidelines during weekly high-performance liquid chromatography quantifications.
Results: The evaluation of insulin efficiency showed that the samples held at different temperatures over the use
period had the same insulin bioactivity as the samples kept at 2°C–8°C. When seen collectively, these findings
show that insulin may be kept at such fluctuating ambient temperatures throughout the typical 4-week usage
period when the patients are unable to find a storage temperature mentioned in label. Conclusion: It is now
feasible to control diabetes more easily in settings with low resources and in humanitarian circumstances by
removing the barrier of cold storage while in use.