Once-daily sustained-release theophylline reduces diurnal variation in spirometry and symptomatology in adult asthmatics.

In 22 adult asthmatics (mean age, 55.2 +/- 15.4 yr), we compared Uniphyl given once a day to Theo-Dur given twice a day using a randomized, double-blind, two-phase crossover trial. All patients demonstrated acute bronchodilator responsiveness (FEV1 increase greater than 15%) to inhaled salbutamol and were dependent upon both orally administered theophylline and inhaled salbutamol at time of entry. Each phase lasted 9 days, the first 2 days of which were a theophylline washout. Uniphyl was given once a day at 8 P.M. and Theo-Dur was given twice a day at 8 A.M. and at 8 P.M. For each patient, the total daily theophylline dose was the same during both phases. Asthma symptoms, drug side effects, and PEFR were recorded at 8 A.M. and at 4 and 8 P.M. each day. On Days 7, 8, and 9 of each phase, serum theophylline concentrations were measured and spirometry was performed at 8 A.M. and at 4 and 8 P.M. The results demonstrated significant differences in both pharmacokinetic and clinical efficacy between the 2 drugs. Uniphyl produced greater "peak" and lower "trough" theophylline concentrations than did Theo-Dur, although both lower "trough" theophylline concentrations than did Theo-Dur, although both drugs maintained concentrations within the accepted therapeutic range. In contrast to the pharmacokinetic findings, Uniphyl was associated with significantly less fluctuation in pulmonary function throughout the day, and the values at 8 A.M. for FEV1, PEFR, and wheeze demonstrated significant clinical efficacy in favor of Uniphyl.(ABSTRACT TRUNCATED AT 250 WORDS)