The consistency of theophylline absorption from a sustained-release formulation in asthmatic children.

Theophylline absorption was studied in asthmatic children ages 2-7 years. A bead-filled capsule of sustained-release theophylline (Slo-Bid, William H. Rorer, Inc., Fort Washington, PA) was administered in equal doses twice daily (8 AM and 8 PM) to produce serum theophylline concentrations (STCs) between 10 and 20 micrograms ml. After 7 days, blood samples were obtained every 2 hours for 24 hours. This sequence was repeated after another seven days of treatment. Elimination values were calculated after an intravenous reference dose. Slo-Bid was completely absorbed (mean +/- SD percentage of dose absorbed of 117.1 +/- 26.1 on day 1, and 104.8 +/- 16.1% on day 2), and the pattern of absorption was consistent from day to day, with maximum STCs occurring 2-6 hours after the dose, and minimum STCs at or near the time of PM dose. The percentage of fluctuation of 149.7 +/- 49.7% and 163.0 +/- 114.0% (mean +/- SD) on days 1 and 2, respectively, was slightly higher than desired, but probably was a result of rapid theophylline clearance in this group of children (119.9 +/- 25.8 ml/hr/kg). Mean residence time for absorption after AM and PM doses indicated significantly longer time for absorption (ta) after the PM doses: mean +/- SEM ta for AM doses on days 1 and 2 was 2.8 +/- 0.3 and 2.7 +/- 0.2 hours, respectively, and increased to 3.9 +/- 0.3 and 3.7 +/- 0.5 hours after PM doses on days 1 and 2, respectively (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)