[Clinical evaluation on glucocorticoid administration in the neurosurgical patients (the third report)--serial plasma cortisol assay following betamethasone 8 mg intravenous injection (author's transl)].

The effect of betamethasone on plasma cortisol concentrations was studied in 6 healty adult men. Each of them was administered 8 mg of betamethasone in a single intravenous injection. Blood samples were obtained serially for 2 days before the injection of betamethasone and for a week after the injection. Plasma cortisol was measured by competitive protein binding analysis. Before the injection of betamethasone plasma cortisol levels showed the normal diurnal rhythm in all the cases. After the injection plasma cortisol levels decreased rapidly and a mean half life time was about 1.7 hours. The low levels of plasma cortisol under 2 microgram/ml were observed for 48 hours after the injection, and then the diurnal rythm of plasma cortisol reappeared, but the levels of plasma cortisol at this time were still lower than the control levels. Then plasma cortisol levles increased gradually and they returned to the control levels 5 days after the injection. Thus, it was clarified that the suppressive effect of 8 mg or betamethasone on plasma cortisol concentrations lasted at least for 48 hours. From this point of view the time interval or repetitive glucocorticoid administration for the treatment of brain edema will further be studied.