Chemical Stability of Epinephrine 10 mcg/mL Diluted in 0.9% Sodium Chloride and Stored in Polypropylene Syringes at 4 degrees C and 25 degrees C

Studies have evaluated epinephrine stability in higher concentrations and shorter durations than we require. The objective of this study was to evaluate the chemical stability of epinephrine in syringes at concentrations of 10 mcg/mL in 0.9% sodium chloride at 4°C and 25°C. Solutions of 10 mcg/mL epinephrine in 0.9% sodium chloride were prepared and stored in 10-mL Becton, Dickinson and Company syringes. Three units of each container were stored at 4°C and 25°C. Concentration analysis was completed on study days 0, 2, 7, 14, 21, 28, 42, 56, 72, and 91 using a validated stability-indicating liquid chromatographic method with ultraviolet detection. Chemical stability was based on the intersection of the lower limit of the 95% confidence interval of the observed degradation rate and the time to achieve 90% of the initial concentration (T-90). The analytical method separated degradation products from epinephrine to measure concentration specifically, accurately, and reproducibly. During the study period, all solutions at 4°C retained more than 89.62% of the initial concentration for 91 days. Solutions stored at 25°C retained more than 90% for 21 days. Multiple linear regression revealed significant differences in percent remaining due to study day (P<0.001) and temperature (P=0.002). The calculated T-90, with 95% confidence, was 71.40 days for solutions stored at 4°C but only 12.77 days for solutions stored at 25°C. We conclude that 10 mcg/mL epinephrine solution diluted in 0.9% sodium chloride stored at 4°C is chemically and physically stable for 64 days, with 95% confidence. The syringe may be held at room temperature for up to 24 hours during this period and still retain more than 90% of the initial concentration.