A comparison of the pharmacokinetics of theophylline in asthmatic children in the acute episode and in remission.

The pharmacokinetics of theophylline following a single intravenous dose of aminophylline were determined in 8 asthmatic patients in each of the acute, the recovery and the remission phase. The overall results for mean plasma theophylline clearance (78.6 +/- 33.3 ml/kg/h), plasma theophylline half-life (4.14 +/- 1.36 h) and apparent volume of distribution (0.41 +/- 0.066 l/kg) are in accordance with previously published values. There was no general statistically significant difference in any of the pharmacokinetic parameters when results from the acute and remission phases were compared. However, certain patients showed reductions in plasma theophylline clearance in the acute phase of the illness such that a dosage regimen standardised during remission may cause toxicity if continued in the acute episode. It is suggested that monitoring the plasma theophylline levels is desirable in all patients in the acute episode.