THEOPHYLLINE PHARMACKIHETICS IN ASTHMATIC CHILDREN AND LTS CLINICAL APPLICATION

Theophylline concentration was assayed by high perfor-mance liquid chromatography. The pharmacokinetics of theophyllinefollowing intravenous injection of aminophylline were determined in 17children with asthma (aged 6y7m-12y3m). The parameters were calculatedby computer with MCPKP program. The average of total clearance oftheophylline was 74ml/h/kg. The biologic half-life of theophylline rangedfrom 3 .5 to 7 .4 hours. The average volume of distribution xvas 0.513 1/kg. The concentration of theophylline and its fluctuation by different usagewere observed. The rational usage of theophylline to asthmatic patient wasprobed. Our results suggest that conventional aminophylline tablets be usedin 5 .5 mg/kg every 6 hours or 8 hours for mild, middle asthma, with totalamount not more than 600-800 mg every day. In this way theophylline con-centration level of most cases would be within the therapeutic concentrationrange, i, e. 10-20μg/ml.