Aerosol bronchodilator therapy: a comparison of the effects of bronkometer with isoetharine, isoproterenol and phenylephrine.

The bronchodilator action and cardiovascular toxicity of aerosols of (1) isoetharine, (2) isoetharine in combination with phenylephrine, (3) isoproterenol, and (4) phenylephrine were compared in a group of severe stable ambulatory asthmatics. All preparations except phenylephrine produced reduction in specific airway resistance and increased flow rates which peaked at 15 minutes. The action of isoproterenol and the two isoetharine preparations peaked at 15 minutes while the peak effect of isoetharine and isoetharine in combination with phenylephrine continued for 60 minutes. The difference between isoproterenol and isoetharine alone or in combination with phenylephrine was not statistically significant. None of the drugs produced any cardiovascular side effects. The authors conclude that isoetharine, though less potent than isoproterenol on a weight-for-weight basis, is an effective and safe bronchodilator. Addition of phenylephrine to isoetharine does not potentiate or prolong the action of the latter.