[An experimental study of the effect of etomidate on central sympathetic activity, respiration and circulation...

The effect of Etomidate on central sympathetic activity, respiration and circulation were studied in animals at rest and under asphyctic conditions. The doses used were 0.15, 0.3 and 0.6 milligrams/kilogram bodyweight. Injection of the drug into animals at rest caused excitation lasting for about 10 seconds and then lowering of sympathetic activity by about 15-30 per cent. With doses of 0.6 mg the depression lasted for about 15 minutes. Central stimulation by asphyxia often a more pronounced dose-dependent depression of sympathetic activity by about 15-40% of the original level was observed. Activity of the phrenic nerve was affected only with doses of 0.6 mg; the reduction by about 30% lasted for up to 15 min. Injection of 0.6 mg was followed within one minute by a short-lasting fall in blood pressure by about 10%. The heart rate remained unchanged at rest but during asphyctic conditions the heart rate was less slowed down than would normally occur with vagal stimulation. Etomidate apparently also depressed the vagal centres. Similarities and differences in action between Etomidate and propanidid are discussed.