Comparison of the bronchodilating action and of the tolerance of fenoterol and isoproterenol aerosols.

Fenoterol aerosol (400 micrograms) and isoproterenol aerosol (200 micrograms) were compared in a double blind cross-over trial in 59 patients with reversible broncho-obstruction. Measurements of VC, FEV1, respiratory impedance (ZR), blood pressure and pulse rate as records of subjective symptoms, râles and side effects, were made over a period of 180 minutes. After fenoterol FEV1 increased significantly from the 15th minute till the first hour. After isoproterenol an increase of this parameter was obtained only at the 15th minute. The decrease in ZR was always larger with fenoterol than with isoproterenol. This difference was significant at the 2nd hour (P < .05) and at the 3rd hour (P < .01). In a group with severe obstruction the airway obstruction improved more with fenoterol than with isoproterenol (P < .01). The functional improvement induced by 400 micrograms fenoterol appeared to be more potent and of longer duration than the improvement caused by 200 micrograms isoproterenol. Moreover it appeared more rapidly after administration.