THE BINDING OF THEOPHYLLINE TO SERUM PROTEIN AND PH IN ACUTE ASTHMA

Aminophyllin is widely used for the teating acute exacerbation of asthma, It is well known that serum pH varies during acute exacerbation of asthma and that serum pH influences the protein binding of theophylline. Therefore, total and free-theophylline and venous pH were measuredin children with acute exacerbation of asthma during pre-and post-aminophylline drip infusion.1. Free-theophylline was correlated with total theophylline.2. The serum pH (7, 337 to 7, 477) had no influence on theophylline protein binding.3. % free theophylline was correlated with total theophylline (r=0, 351, P<0.01).4. We studied the effect of age on % free theophylline, % free theophylline was 40.4±4.1% for 1 to 7 year olds, 33.1±3.9% for 6 to 11 year olds and 31.1±17.7% for those over 12 year olds. There was a positive relationship between age and the fall of % free theophylline, however, there was no correlation between % free theophylline and age.