Pharmacokinetic analysis of concentration-time data obtained following administration of drugs that are recycled in the bile.

A pharmacokinetic model for calculating the pharmacokinetic parameters for a compound that is recycled in the bile is presented and tested using theoretical as well as experimental data. The results indicate that this method is stable and only slightly susceptible to sampling and recycling times. It is apparent from the present study that pharmacokinetic terms that have been used in classical situations are not directly applicable to drugs that enter the enterohepatic circulation. Effective half-life and effective clearance are used to describe the intrinsic ability of the eliminating organs to remove drug from the blood, whereas net half-life and net clearance are used to describe the irreversible elimination of the drug from the body.