Effect of ephedrine-isopropylantipyrine (EIA) on exudative inflammations and its physiological mechanisms were examined. When given to rats in a dose of 0.65 mmole/kg, EIA showed stronger inhibitory effect like phenylbutazone than isopropylantipyrine (IA) or ephedrine, on edema produced by carrageenin, formalin, and dextran, and increased vascular permeability induced by histamine and xylene. This compound greatly inhibited the primary edema by carrageenin in a rat, and its inhibitory action was blocked by reserpine and dibenamine. EIA also inhibited prostaglandin synthesis in vitro in 25 μM of ED50, equal to phenylbutazone and more than IA, in proportion to their inhibitory effect on exudative inflammation. Further, this compound promoted the excretion of noradrenaline into rat urine less than ephedrine and increased the level of cyclic AMP in lung and spleen of a rat. Anti-inflammatory action of EIA seems to result from inhibition of prostaglandin synthesis and moderate stimulation of sympathetic nerve system. EIA showed an antitussive effect and its ED50 was 23.1 mg/kg in guinea pigs, and improved the stimulated function of adrenal cortex system in a rat under stress by altera-tion of rhythm in temperature, but did not show a spontaneous motor activity like ephedrine and any effect on adrenal cortex function and blood glucose level of a normal rat.
