[Examination of theophylline pharmacokinetics during an attack of bronchial asthma in children].

ABSTRACT

For the purpose of a safe and effective use of theophylline in therapy during an attack of asthma, we have examined the effect of an attack of bronchial asthma on the metabolism of theophylline. We carefully selected cases in which neither theophylline preparations have been administered, nor infectious complications have occurred, nor an attack has been delayed. Aminophylline was intravenously administered to 33 asthmatic children by instillation over 2 hours during an attack of asthma and during a phase of remission, then a concentration of theophylline in blood was determined without further administration of theophylline, and a distribution volume of theophylline, its half-life, its elimination rate and its clearance were calculated. The results obtained are as follows. The volume of distribution of theophylline was 0.572 +/- 0.076 L/kg during and attack while it was 0.458 +/- 0.116 L/kg during a phase of remission. During an attack, the volume of distribution of theophylline increased. The half-life of theophylline was 7.741 +/- 3.313 hr. during an attack while its was 4.710 +/- 1.873 hr. during a phase of remission. During an attack, the half-life of theophylline increased while the elimination rate constant decreased. The clearance of theophylline was 57.4 +/- 20.9 ml/kg/hr. during an attack while it was 78.3 +/- 31.0 mg/kg/hr. during a phase of remission. During an attack, the clearance of theophylline increased. As described above, during an attack, a distribution volume of theophylline increases, its elimination rate constant decreases, and its clearance is prolonged.(ABSTRACT TRUNCATED AT 250 WORDS)