Efficacy of maintenance of therapeutic serum concentrations of theophylline in chronic asthma.

The efficacy of maintenance theophylline therapy at serum concentrations ranging between 8 and 20 micrograms/ml was studied over a six-month period in a group of 100 outpatients (age range 18-80 years) with chronic asthma. The study was satisfactorily completed by 95 of the individuals. Theophylline therapy led to a progressive disappearance of the patients' clinical signs and symptoms. A significant improvement in pulmonary function was observed in all patients, which was related to the initial degree of airway obstruction. The improvement was more pronounced at the start of treatment. At the end of the study there were still anomalies in the respiratory parameters in those patients who originally showed greater pulmonary compromise (FEV1 less than 50% of the predicted value) which seemed to indicate persistent airway obstruction. However, the improvement shown by these patients was sufficient for them to carry out their normal daily activities. We conclude that controlled long-term therapy with theophylline may be beneficial for outpatients with chronic asthma.