1980 Volume 29 Issue 5 Pages 203-210
The validity and predictability of theophylline pharmacokinetics obtained from the initial i.v. loading were examined for the optimization of oral theophylline therapy in 40 asthmatics and 7 congesve heart failure (CHF) patients. Based on individual disposition data, adjusted dosage regimens were undertaken for each patient and the predicted plasma theopylline concentrations were compared to those actually measured by a high pressure liquid chromatography (HPLC). No significant difference of the apparent volume of distribution was found between the two groups. However, the elimination half-life (17.4±1.7hr, mean±SEM) and plasma clearance (0.016±0.001l/kg/hr) in CHF patients differed significantly (p<0.01) from those of patients with uncomplicated bronchial asthma. Out pharmacokinetic data indicated that a loading dose of aminophylline (4.5-5.0mg/kg), followed by a maintenance dose (0.46 and 0.20mg/kg/hr, iv.infusion rate), is the recommended regimen for asthmatic and CHF patients (cardiac asthma), respectively. The predicted concentrations at steady-state for attaining the therapeutic range of 8-20μg/ml were consistent with the observed levels and the predicted ability for maintaining this therapeutic range was achieved in 74% of the examined patients. We conclude that for optimization of theophylline therapy, an understanding of the clinical pharmacokinetic principles is necessary and this approach may lead to more rational dosage regimen adjustments of theophylline.
