Intersubject variability of serum theophylline concentration after single dose of uncoated controlled release theophylline tablet administration in asthmatic patients.

ABSTRACT

Various reports indicate significant intersubject variation in the rate of absorption of controlled release theophylline products that are commercially available. Serum theophylline concentration was estimated in 17 asthma patients treated with controlled release theophylline tablet (mean dose 5.6 +/- 0.6 mg/kg, mean body wt 49.82 +/- 9.05 kg). The mean maximal concentration (Cmax) of 5.57 +/- 1.65 micrograms/ml occurred at mean time of maximal concentration (Tmax) of 3.3 +/- 1.36 (mean +/- SD) hours. Mean minimal concentration (Cmin) was 3.164 +/- 1.1 micrograms/ml (mean +/- SD) at mean time of minimal concentration (Tmin) of 5.77 +/- 1.77 (mean +/- SD) hours. The mean percent fluctuation was 112.95 +/- 183.45 (mean +/- SD) but in 4 out of 17 patients, percent fluctuation was 107.29 to 823.10. Therefore, 23.5% patients treated with controlled release theophylline tablet had wide fluctuations in serum theophylline concentration.