Serum drug fluctuations after administration of two sustained-release oral theophylline preparations in asthmatic children.

Serum theophylline levels produced by two bands of sustained-release theophylline tablets, TheoDur and Respbid, were compared in a double-blind crossover study in 13 asthmatic children. The children, aged 9 to 17 years, remained involved in their daily school activities throughout the study. Each patient took 250 mg every 12 hours of one brand of anhydrous theophylline for five days and the other preparation for the remaining five days of the ten-day study. Trough and peak theophylline levels at steady state were measured on the fifth and tenth days of the study. Results indicated no significant differences between peak and trough with either preparation and no difference between the two preparations in mean theophylline concentrations.