CONVERSION FROM TWICE-DAILY TO ONCE-DAILY EXTENDED-RELEASE THEOPHYLLINE TREATMENT IN PATIENTS WITH REVERSIBLE AIRWAY-OBSTRUCTION

This multicenter, randomized, investigator-blinded, parallel group stu dy compared the effects of converting patients from a q12h extended-re lease theophylline preparation (Theo-Dur(R)) to a q24h extended-releas e product (Uni-Dur(R)). Patients (n = 133) first received open-label T heo-Dur treatment with dosage titrated to achieve peak serum theophyll ine concentrations of 10-20 mu g/ml. Patients then were randomized to continue Theo-Dur (n = 64) or to convert to Uni-Dur (n = 60) with peak serum theophylline concentrations maintained in the desired range. Pu lmonary function tests were performed during the open-label and blinde d periods; patients maintained diaries and performed peak flow measure ments before each dose of study treatment. Adverse events were recorde d throughout the study. Respiratory status during blinded treatment wa s rated as the same or improved compared with open-label treatment by >87% of evaluable patients and physicians, regardless of treatment gro up. There were no significant differences in mean peak serum theophyll ine concentrations at baseline, at the final evaluation, or at any poi nt during the study. Few dosage adjustments were necessary (5/52, Uni- Dur; 9/57, Theo-Dur). There were no significant changes in pulmonary f unction test results or patient diary entries between the open-label a nd blinded periods. Headache and nausea were the most commonly reporte d adverse events. In conclusion, converting patients from twice- to on ce-daily theophylline treatment resulted in no significant changes in any measures of pulmonary function, and there were no significant diff erences between the groups during the blinded treatment period.