Effects of parenteral aminophylline on lung mechanics in normal human.

We studied the effects of an intravenous injection of 5.0 mg of aminophylline per kg of body weight on lung mechanics in 8 normal subjects. No change occurred in lung volumes, airway resistance, and maximal expiratory flow-volume and lung pressure-volume curves. Restudy of 4 of the subjects before and after an injection of 8.0 mg/kg of aminophylline did not modify the pattern of response to the drug, despite a serum concentration range of 15.1 to 19.3 mg/l. These findings were, therefore, in contrast with those observed after the administration of atropine or beta-2 adrenergic derivatives. They suggested that the bronchodilator effects of aminophylline may not be due to a direct action of the drug on the bronchial smooth muscle.