Although the clinical features of exercise-induced asthma (EIA) have been clearly described, the pathophysiology is incompletely understood. This review addresses some of the current concepts about the pathogenetic mechanisms of EIA and their implications for treatment of this problem.
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)
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