ABSTRACT
Characterization of the pharmacokinetic behavior of drugs in the body is important in determining the drug concentration-time prole and predicting the therapeutic and toxic effects after administration of different dosing regimens by different routes of administrations. The pharmacokinetic behavior of drugs in the body depends on a variety of factors including the drug physicochemical properties, blood ¥ow to different organs, the ability of the drug to cross the biological membranes, the afnity of the drug to different tissues, and the ability of some organs to eliminate the drug. The compartmental pharmacokinetic models have been used to describe the pharmacokinetic behavior in the body by dividing the body into a number of interconnected compartments without identifying the organs and tissues that make up each compartment. This approach utilizes the observed drug concentration in the systemic circulation and other biological ¥uids to select the best compartmental model that can describe the drug pharmacokinetics. The estimated pharmacokinetic parameters for the compartmental model can be used to describe the drug concentration-time proles in the central and peripheral compartments that can be linked to the observed drug effects after drug administration. On the contrary, the noncompartmental approach, which can be used when the drug elimination follows rst-order kinetics, describes the general drug pharmacokinetic behavior without the exact characterization of the drug concentration-time prole. This approach can
be useful when comparing the in vivo performance of different dosage forms, the rate and extent of drug absorption from different routes of administration, and the pharmacokinetic behavior in different patient populations. It is also useful for bioequivalence testing, studying drug-drug interactions, and other pharmacokinetic investigations that do not require determination of the time course of the drug concentration in the body. Both the compartmental and noncompartmental modeling approaches provide important and useful information about the drug pharmacokinetics in the body.
