Modelling theophylline response in individual patients with chronic bronchitis.

1 In six patients with chronic bronchitis, serial changes in both ventilatory function and plasma theophylline concentrations were measured simultaneously for 8 h following 500 mg aminophylline intravenously. 2 Using empirical mathematical models which can integrate this data, parameters were estimated which can express response as a linear function of steady state plasma theophylline levels. 3 Taking Forced Vital Capacity (FVC) as the target response, the mean (+/- s.d.) increase in FVC was 0.06 +/- 0.02 l/micrograms ml-1, starting with pretreatment values in the range 1-21. 4 This analytical approach could be used to determine whether or not a patient with chronic bronchitis could obtain a satisfactory response to theophylline at plasma levels normally encountered in clinical practice.