The differential effects of MOC-carboetomidate (27 mg/kg) and etomidate (2 mg/kg) on adrenocortical function in the rat. These doses correspond to twice the respective ED50s for loss of righting reflexes. Adrenocorticotropic hormone1–24 was given simultaneously with sedative-hypnotic to stimulate corticosterone production and serum corticosterone concentrations were measured 30 minutes later. Four rats were studied in each group. Average corticosterone concentrations (±SD) were 460 ± 140 ng/ml in the vehicle control group, 90 ± 44 ng/ml in the etomidate group, and 610 ± 280 ng/ml in the MOC-carboetomidate group. *, P < 0.05; **, P < 0.01; NS, no significant difference.