Aminophylline increases the toxicity but not the efficacy of an inhaled beta-adrenergic agonist in the treatment of acute exacerbations of asthma

We studied 40 patients with acute exacerbations of asthma to determine the efficacy of a 3-h intravenous infusion of aminophylline in patients who were already being treated with an inhaled beta-adrenergic agonist (metaproterenol). Each patient was treated with inhaled metaproterenol at hourly intervals for 3 h. In addition, patients were randomly assigned to therapy with either intravenous aminophylline or placebo. Neither the patient nor the house officers and nurses caring for the patients knew whether aminophylline or placebo was given. The FEV₁ improved continually throughout the study to a similar extent in both treatment groups, but the patients treated with aminophylline had significantly more adverse effects (p < 0.025, Mann-Whitney). There was no apparent benefit from aminophylline even in patients who presented to the emergency room with severe airway obstruction (FEV₁ < 0.8L) or with plasma theophylline levels <10 mg/L. We conclude that intravenous aminophylline adds to the toxicity but not the efficacy of inhaled metaproterenol in the treatment of acute exacerbations of asthma.