Physical and Chemical Compatibility of Etomidate and Propofol Injectable Emulsions

The mixture of etomidate and propofol is widely used in clinical practice to improve efficacy of general anesthesia and to minimize side effects. As a thermodynamically unstable system, emulsion is prone to destabilization through mechanisms including coalescence, flocculation, and creaming. Such unwanted phenomenon can induce fat embolism after intravenous administration. This study was aimed to investigate the physical and chemical stability of the mixture of etomidate and propofol in the dosage form of emulsion.This compatibility study focused on the critical quality attributes (CQAs) of drug-containing emulsions, such as appearance, pH, particle size and distribution, zeta potential, the observation under centrifugation, and drug content and impurity.As the results, there were no significant changes in the CQAs of the mixed emulsions up to 24 h after mixing at refrigeration temperature (4°C), room temperature (25°C), and body temperature (37°C).These results demonstrate that etomidate emulsion is physically and chemically compatible with propofol emulsions up to 24 h at 4°C, 25°C, and 37°C, suggesting that etomidate and propofol can be administrated in mixture without adversely affecting product characteristics, at least in vitro.