Purpose: The effects of wide temperature variations on the stability of atropine, epinephrine, and lidocaine stored under field conditions in advanced life support (ALS) paramedic units were evaluated.
Methods: Vehicles from various ALS paramedic units were selected throughout Los Angeles County, California, including desert, marine, and helicopter-based divisions. A temperature-recording device was placed in the compartment where drugs are stored and used to record and store temperature data at 15-minute intervals. Three autoinjector-style syringes of atropine, epinephrine, and lidocaine were taken from stock for each ALS unit and placed in each vehicle, while three control syringes were stored in the laboratory under controlled conditions. Six samples of each drug were withdrawn at time 0 and on days 5, 10, 15, 30, and 45. Samples were analyzed using high-performance liquid chromatography. Stock solutions, created using analytical grade atropine, epinephrine, and lidocaine, were used to construct 5-point standard curves to determine the drug concentration of each sample.
Results: Seven sites exceeded 104 degrees F (40 degrees C) for as little as 30 minutes and as long as 795 minutes. Ten of the sites achieved a mean kinetic temperature (MKT) above 77 degrees F (25 degrees C), with the highest MKT calculated being 84.1 degrees F (28.9 degrees C) over a 45-day period. There was no evidence of drug degradation at any site, at any temperature, or at any time point.
Conclusion: Atropine, epinephrine, and lidocaine can be stored at temperatures of up to 84.1 degrees F (28.9 degrees C) for up to 45 days and tolerate temperature spikes of up to 125 degrees F (51.7 degrees C) for a cumulative time of 795 minutes (13.25 hours) without undergoing degradation.