Emergency care drugs' chemical stability after eight weeks' deployment in the prehospital setting

Temperature conditions vary in emergency service vehicles, which may pose a risk to the integrity of the drugs on board, possibly rendering them ineffective and increasing morbidity and mortality in patients.

This study assessed the stability of four emergency care drugs (adrenaline, etomidate, ketamine, and rocuronium) after eight weeks of deployment in the prehospital context.

The study adopted a longitudinal quantitative design to evaluate the chemical stability of emergency care drugs. The study was conducted at four emergency medical service bases in Ballito, Durban and Pietermaritzburg, South Africa. The primary outcome was the relative reduction in drug concentration from the labelled concentration after four and eight weeks. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analysed samples to determine the concentration of active ingredients in the drug samples.

HPLC analysis was done on 176 samples. The ambient temperature ranged from 18.7 to 44 °C in the first four weeks, averaging 26.8 °C ± 3.0. At 4 and 8 weeks, Adrenaline decreased 24.93 % and 22.73 %, respectively. Etomidate's control had 3.06 mg/ml, not the 2 mg/ml on the bottle. After 4 and 8 weeks, the samples had 3.10 and 3.15 mg/ml active components, respectively. Ketamine degraded over 30 % after four weeks but not beyond that. The Ketamine package states 10 mg/ml. However, we found 17.46 mg/ml. Rocuronium was 6.45 mg/ml in the control, although the manufacturer specified 10 mg/ml. At four weeks, the concentration was 6.70 mg/ml; at eight weeks, 6.56.

This study suggests that adrenaline and ketamine degrade by more than 20 % within four weeks of deployment in the prehospital field, whereas etomidate and rocuronium remain stable after eight weeks.