Double-blind comparison of metaproterenol and isoetharine-phenylephrine solutions in intermittent positive pressure breathing in bronchospastic conditions.

A 5 percent solution of metaproterenol sulfate (Alupent) and a fixed-combination solution of isoetharine and phenylephrine were compared in a single-dose double-blind study in a total of 27 patients with reversible bronchospastic disease. The patients were assigned to parallel groups for treatment and received the usual dose of 0.3 ml of metaproterenol and 0.5 ml of the isoetharine-phenylephrine solution via equipment for intermittent positive-pressure breathing. Tests of pulmonary function, blood pressure, and pulse rate were performed before the treatment and at intervals of 30 minutes to six hours after administration. The duration of effect (defined as an increase over baseline in the forced expiratory volume in one second [FEV1] of at least 15 percent) of metaproterenol averaged four hours, as compared with one hour for the reference solution. The overall response of FEV1 to metaproterenol was significantly (P = 0.01) superior to the response to the isoetharine-phenylephrine solution. Metaproterenol also surpassed the reference drug in terms of increases in the mean forced expiratory flow during the middle half of the forced vital capacity (FEF-25-75%) to a degree approaching statistical significance. Changes in blood pressure and pulse rate were clinically insignificant with both drugs, and the total number of adverse experiences was substantially the same with both solutions.