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

Abstract

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 (T) 125 mg, ephedrine SO4 (E) 30 mg, T + E, or placebo were given in a randomized, double-blind, crossover design on 4 separate days. Pulmonary function tests (FVC [forced vital capacity], FEV1 [forced expiratory volume at 1s], FEF25-75 [mid-maximal expiratory flow rate]) and serum T levels were determined at 0, 4, 1, 2, 4 and 6 h on both day 1 and after day 7 of an every-6-h drug dosage schedule. Mean maximum T levels were achieved at 2 h with a peak mean of 2.94 .mu.g/ml .+-. 0.24 SEM [standard error of the mean] on day 1. On day 8, the maximum T levels were higher, with a peak mean at 2 h of 4.69 .mu.g/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 2-5 .mu.g/ml. Addition of E to the T regimen further improved pulmonary function only on day 1 and had no effect on the last study day.