Evaluation of the tissue-to-blood partition coefficient R for physiological pharmacokinetic models

The tissue-to-blood partition coefficient R, fraction of drug unbound in blood fB and intrinsic clearance of elimination organ/tissue Cl'L are important parameters used in physiological pharmacokinetic models. Simple equations to evaluate R by AUC were derived in this paper for single bolus iv, the tissue-to-blood partition coefficient of nonelimination organ/tissue was exactly the ratio of AUC between tissue and blood, those equations were examined by the experimental data of rats following iv ethoxybenzamide 20 mg.kg-1, and compared with other methods. Equations to evaluate fBCl'L and other parameters were also given for linear elimination model.