INDIVIDUALIZATION OF THEOPHYLLINE INFUSION RATE ON THE BASIS OF A NONLINEAR COMPARTMENTAL PHARMACOKINETIC MODEL

In the present paper, a nonlinear compartmental model for theophylline pharmacokinetics is developed. The analytical solution of the model, in parametric form, is derived under plateau conditions for plasma met abolite concentration. The parameters are obtained from plasma and uri ne data using best fitting techniques and their values are used in ord er to calculate maintenance intravenous infusion. Numerical simulation is then performed in order to compare the drug concentration obtained by our approach with that of alternative intravenous regimens. The di fferences argue for individualized dosage regimens, since theophylline is a drug with a narrow therapeutic window and its concentration at t he active sites strongly depends on characteristic parameters of the p atient's response. Our results show that it is possible to estimate th e patients' parameters during the first 8 h after intravenous administ ration of the drug and these parameters can be used to design an indiv idualized dosage regimen in patients receiving theophylline intravenou sly.