Clinical efficacy of two beta 2-sympathicomimetics in different inhalers in children with asthma. Comparison of pirbuterol in a breath-actuated inhaler and salbutamol in a customary metered-dose inhaler.

In a controlled clinical crossover trial, the therapeutic effect of pirbuterol (CAS 38677-81-5) in the Autohaler was compared to that of salbutamol in a customary metered-dose aerosol in 17 children with asthma. Each child was randomized to both treatments with a washout period of at least 1 day and at most 13 days. Ten children commenced with salbutamol and then switched over to pirbuterol, and the other 7 vice versa. The main criterion to evaluate efficacy was the forced expiratory volume after 1 s (FEV1). Other efficacy criteria were forced vital capacity (FVC) and peak expiratory flow (PEF). The patients were given detailed instructions on how to use the inhalers. Each treatment was applied in the morning with one shot (0.2 mg pirbuterol or 0.1 mg salbutamol). FEV1, FVC and PEF were measured in all patients 10 min before and 10 min after medication with the whole-body plethysmograph; further measurements were carried out in most patients 60 and 240 min after application. There was a mean increase of 47% in the FEV1 compared to baseline with pirbuterol in the Autohaler compared to a mean increase of only 30% with salbutamol in the customary metered-dose inhaler. The difference is statistically significant (p = 0.036). A linear crossover analysis showed a significant treatment effect 10 min after application in favour of pirbuterol with no significant period effects or interactions (p = 0.020). The increases of FVC and PEF after pirbuterol treatment were also remarkably higher than after salbutamol. No side effects were observed.