Etomidate reversibly depresses human neutrophil chemiluminescence

The effect of etomidate on human neutrophil chemiluminescence was evaluated. The latter is an index of oxygen free-radical generation, which is an important bactericidal mechanism. Five drug concentrations representing the free plasma concentrations ranging from deep anesthesia (0.5 microgram/ml) to the plasma level that may be found approximately 1 h after an etomidate anesthetic (0.0156 microgram/ml) were studied. The importance of the duration of drug incubation was assessed by incubating the neutrophils with the drug concentrations for 10, 20, 30, 40, or 50 min before stimulation. The reversibility of any depression in chemiluminescence was assessed by gently washing the cells twice after incubation and then stimulating them. The two higher etomidate concentrations (0.5 microgram/ml and 0.125 microgram/ml) produced reductions in chemiluminescence of 43% and 35%, respectively (P less than 0.05). The reductions in activity only occurred when the cells had been incubated with etomidate for 50 min and were completely reversed by washing. These results show that clinically relevant concentrations of etomidate will reversibly depress neutrophil chemiluminescence in vitro when the cells are exposed to the drug for more than 50 min.