Maximum bronchodilator effect of pirbuterol and procaterol administered as sprays with and without an aerochamber

To determine the maximal bronchodilator dose of procaterol and pirbuterol administered by inhalation with an without an aerochamber (Aerocâmera) to children with acute bronchial asthma attacks.

Prospective. 18 children (6-15 years of age) with acute bronchial asthma attacks (FEV1 < 80% of the predicted value) received pirbuterol (N = 10) or procaterol (N = 8) by metered-dose inhaler, one puff every 5 minutes, for a total of five doses. During another acute attack, the same patient received the same medication with the aid of a spacer (Aerocâmera). Clinical evaluation and pulmonary function tests were performed 5 minutes after each inhaled dose.

For both drugs, maximal bronchodilation was obtained after the second dose. No significant side effects were observed even after procaterol doses of 50 micrograms or pirbuterol doses of 1000 micrograms. The results were unaffected by the use of the spacer.

The doses that induced maximal bronchodilation were 400 micrograms pirbuterol and 20 micrograms procaterol. Although the spacer did not change the results, it is a valuable aid for patients who have difficulty in using the metered-dose inhaler (M.D.I.).