Evaluation of a Sustained-Release Theophylline Tablet in Young Asthmatics

Abstract

A sustained-release theophylline (SRT) tablet was evaluated in 15 children with moderately severe asthma between the ages of 3 and 5 years (4.2 +/- 0.83 years). They received a mean daily dose of 20.4 mg/kg given q12h for 3 or more weeks with daily symptom scores and twice daily peak flow rates (PFR) measured. Serum theophylline levels (STL) were then obtained at 0, 1, 2, 4, 6, 8, 10, and 12 hr (eight children had 24-hr samples obtained), along with PFRs every 3 hr. The mean peak STL (x +/- SD) was 16.6 +/- 4.4 and the trough was 5.9 +/- 2.8, with a peak-trough difference of 10.6 +/- 3.9. The average time to peak level was 3.9 hr. The mean +/- SD clearance was 1.42 +/- 0.63 ml/kg per min and the apparent T1/2 was 5.11 +/- 1.34 hr. The average weekly morning PFR for the 3-week period ranged from 116.8 +/- 41.2 to 127.4 +/- 37.4 L/min, and the evening PFT ranged from 126.5 +/- 38.4 to 137.0 +/- 40.9 L/min. In conclusion, the SRT tablet is effective in treating many young asthmatics on a 12-hr dosage schedule. For some children who experience excessive peak-trough differences, an 8-hr dosage schedule may be indicated.