Pharmacokinetics of theophylline before and after nephrectomy in dogs.

The role of the kidneys in the elimination of theophylline was directly assessed using nephrectomized dogs. Data was analyzed by two different pharmacokinetic approaches. Analysis indicated that a given dosage regimen produced significantly different serum concentrations before and after nephrectomy. Model independent pharmacokinetic analysis failed to show a significant difference in parameters. A model dependent approach, using a nonlinear regression analysis employing a linear two-compartment model, demonstrated that the differences observed could be accounted for by a change in the first order elimination kinetics.