Stability Of Epinephrine In A Normal Saline Solution

Objectives: By law, pharmaceutical companies clearly label their medications with an expiration date, but there is still debate behind the “new expiration date” after a drug has been diluted. Some medications, either for storage or preservation, commonly come in concentrations which are unusable for clinical anesthesiology and epinephrine falls into this category. Unfortunately, epinephrine is generally used during emergency situations making it difficult to perform an urgent dilution amidst a declining clinical scenario. Emerging evidence indicates that not only do medications remains stable past their original pharmaceutical expiration date but even after diluting, their stability remains intact. The objective of this study was to determine the stability of epinephrine over time in a 10cc normal saline pre-filled syringe stored in a practical clinical setting
Methods: All samples were prepared by diluting 1 mg/cc of epinephrine to 10mcg/cc by using normal saline pre-filled syringes. The samples were then left for 90, 60, 30, 15, 7, 3, 1, and 0 day(s) prior to final analysis and stored in one of four different laboratory environments to emulate clinical scenarios (light, dark, room temperature, and refrigerated). Capillary electrophoresis was then used to measure the chemical degradation of epinephrine over time. Additionally, agar plating was used to measure bacterial growth in all samples.
Results: There were no differences in the chemical degradation of epinephrine stability between 0 and 90 days in any of the four different environments. Additionally, no bacterial growth was detected in any of the samples.
Conclusions: Epinephrine remains stable in a normal saline pre-filled syringe for up to 90 days in common settings of lighting and temperature. Therefore, pre-diluting epinephrine for anticipated clinical emergencies may remain clinically useful for up to 90 days, thus improving both patient safety and overhead costs.