Comparison of the Bronchodilator and Cardiac Effects of Hydroxyphenylorciprenaline and Orciprenaline

¹ Department of Medicine, University of British Columbia, Vancouver General Hospital, Vancouver, B.C., Canada

The bronchodilator and cardiac effects of hydroxyphenyl-orciprenaline (H-P-orciprenaline) and orciprenaline given by inhalation were compared in 20 patients with asthma in a double-blind study. Ten patients were given 0.4 mg of H-P-orciprenaline and 1.5 mg of orciprenaline by inhalation, while the remaining ten were given double the dose of each drug. Both drugs resulted a marked improvement in forced expiratory volume in one second, forced vital capacity, maximum flow at 50 percent of the vital capacity and airway conductance. The bronchodilator activity of H-P-orciprenaline was greater and more prolonged than that of orciprenaline. Its action showed no evidence of waning after three hours. No real advantage was shown in doubling the dosage of either drug. Inhalation of 0.8 mg of H-P-orciprenaline caused tachycardia in two patients, one of whom had associated heart disease. Both drugs appeared to act on the smooth muscle of the large and the small airways as airway conductance and maximum expiratory flow rate both improved to a considerable extent.