Clinical pharmacodynamics of theophylline.

The clinical pharmacodynamics of theophylline, which concerns the correlation between the serum theophylline concentration ([TH]) attained during therapy for asthma and improved pulmonary function or unwanted side effects, serves to link the pharmacokinetics of theophylline with the time course of clinical outcome. Although the minimum effective and maximum safe [TH]s have been known for some years, it was only recently shown that maximal improvement in pulmonary function lags behind rapidly changing [TH]s and that improved pulmonary function relates to increasing [TH]s within the therapeutic range. While much is known about the determinants of theophylline disposition in patients with asthma, enabling individualized pharmacokinetically based therapy, it is difficult to predict the clinical pharmacodynamic outcome. Investigation of the effects of age, cardiopulmonary disease, concurrent drugs, diet, circadian rhythms, and other patient features on theophylline clinical pharmacodynamics may provide a basis for prediction of individual patient responsiveness to theophylline and lead to further optimization of theophylline therapy in asthma.