Short-acting versus a long-acting preparation of theophylline ('Xantivent') in the treatment of reversible bronchospasm.
A study was carried out in 30 patients with chronic obstructive pulmonary disease to compare the effectiveness and tolerance of a standard theophylline preparation given 4-times daily with that of a long-acting preparation given in comparable dosage twice daily. All patients were treated for the first 2 weeks with the standard theophylline and dosage was adjusted to optimal levels according to individual patient tolerance. Patients were then treated for the following 2 weeks with the long-acting theophylline preparation. Mean daily dosage was 10.82 mg/kg body weight during the standard and slightly lower at 9.90 mg/kg during the long-acting theophylline treatment periods. Assessments of clinical symptoms and measurements of pulmonary functions were made on entry and at the end of each treatment period, and theophylline serum levels were determined at 0 hour and 5 hours after the last dose. The results showed that the improvement in clinical symptoms was significantly more pronounced after the long-acting theophylline period. In addition, pulmonary functions also showed a greater tendency for improvement after this period. The long-acting preparation was better tolerated and therapeutic theophylline serum levels of 10 to 20 micrograms/ml were achieved at 0 hour of dosing in 36.7% and at 5 hours of dosing in 60.0% of all patients, while therapeutic serum levels were achieved only in 6.7% and 20.0%, respectively, after the standard theophylline. The optimal starting dose of the long-acting theophylline preparation ('Xantivent') appeared to be between 11 and 13 mg/kg body weight to achieve therapeutic serum levels over 24 hours.