The effectiveness of the short- and long-term use of crystallized theophylline in asthmatic children.

The bioavailability, duration of action, and efficacy of a crystallized tablet form of theophylline were studied in 16 nonsteroid-dependent asthmatic children. All required bronchodilator drugs daily for control of symptoms. Theophylline 125 mg, ephedrine SO4 30 mg, T + E, or placebo were given in a randomized, double-blind, crossover design on four separate days. Pulmonary function tests (FVC, FEV1, FEF25-75) and serum T levels were determined at 0, 4, 1, 2, 4, and 6 hours on both day one and after day 7 of a every-six-hour drug dosage schedule. Mean maximum T levels were achieved at two hours with a peak mean of 2.94 microgram/ml +/- 0.24 SEM on day one. On day 8, the maximum T levels were higher, with a peak mean at two hours of 4.69 microgram/ml +/- 0.49 SEM. Computer analyses for pharmokinetics are compatible with 100% absorption of this preparation. Pulmonary function tests were significantly improved (FEV1 20% and FEF25-75 15%) at T levels of 2 to 5 microgram/ml. Addition of E to the T regimen further improved pulmonary function only on day one and had no effect on the last study day.