Efficacy and Side Effects of Beta₂-Agonists by Inhaled Route in Acute Asthma in Children: Comparison of Salbutamol, Terbutaline, and Fenoterol

Abstract

Thirty-seven separate episodes of acute bronchial asthma were studied in 21 asthmatic children. The bronchodilator, cardiovascular, and tremorigenic responses following administration of salbutamol (SAL), terbutaline (TER) and fenoterol (FEN) by closed-port intermittent nebulization were compared for a period of 8 hr. SAL was used at the maximum dose recommended by the manufacturer and TER and FEN at the average doses commonly used in children. Eleven acute attacks were treated with SAL, 12 with TER, and 14 with FEN. Pulmonary function was evaluated by clinical assessment and by the spirometric indices FEV₁ and FEF_25-75. Tremor was objectively measured, as well as heart rate (HR), respiratory rate, and blood pressure. The onset of bronchodilating effect occurred at 5 min for all three drugs and there were no differences in intensity and duration of bronchodilation between drugs. All three drugs caused rapid onset of tremor (5 min) and this tended to be more intense with SAL. There was a slight decrease in HR in the TER group, whereas SAL and FEN caused increase in HR, with mean values significantly greater than in the TER group from 5 to 30 min after drug administration. Our results indicate that the three short-acting beta₂-agonists studied are equally effective in treatment of acute bronchospasm by the inhaled route in children, in the doses used. Our findings imply that a dose of SAL twice as great as that commonly used by nebulization in children is equipotent to those usually employed for TER and FEN, as far as therapeutic effect is concerned, but it could generate more intense tremorigenic and tachycardic side effects.