Impact of temperature exposure on stability of drugs in a real-world out-of-hospital setting.

Study Objective: The aim of this study is to determine the content of 5 important emergency medical services (EMS) drugs after being stored at the recommended refrigerated temperature, room temperature, or in an emergency physician transport vehicle operating under real-world working conditions.

Methods: Adrenaline hydrochloride, cisatracurium besylate, lorazepam, methylergonovine maleate, and succinylcholine chloride were stored for 1 year under the 3 conditions. For each storage condition, samples of the drugs were taken after 1, 2, 3, and 4 weeks and after 2, 4, 6, 8, 10, and 12 months. For adrenaline hydrochloride, however, the samples were taken after 1, 2, 4, 6, 8, 10, and 12 months. The samples were analyzed with a validated high-performance liquid chromatography assay. A drug was considered stable if its content was above 90%.

Results: Adrenaline hydrochloride and methylergonovine maleate remained stable for 1 year at room temperature and in the emergency physician transport vehicle. At room temperature and in the emergency physician transport vehicle, lorazepam became unstable within 4 weeks. Succinylcholine chloride was stable for 2 months at room temperature and for 1 month in the emergency physician transport vehicle. Cisatracurium besylate became unstable within 4 months at room temperature. However, it remained stable for 4 months in the emergency physician transport vehicle.

Conclusion: When stored at room temperature or in the emergency physician transport vehicle, lorazepam became unstable within weeks, whereas succinylcholine chloride and cisatracurium besylate became unstable within months. Adrenaline hydrochloride and methylergonovine maleate remained stable for several months, even under room temperature and emergency physician transport vehicle conditions. Thus, real-world EMS working conditions pose challenges for maintaining optimal efficacy of these important EMS drugs.