**Preface to "Drug Metabolism/Transport and Pharmacokinetics"**

Clinically important phase I and II metabolizing enzymes, such as the cytochrome P450s (CYP) and UDP-glucuronosyltransferase (UGT) families, and drug transporters from two major superfamilies, ATP binding cassette (ABC) and Solute carrier (SLC) transporters, play pivotal roles in the pharmacokinetics, pharmacogenomics, and the drug–drug interactions of therapeutic drugs, as well as herbal medicines. Therefore, researchers and regulatory agencies have made great efforts to understand the underlying mechanisms for the pharmacokinetic determinants, pharmacogenomic features, and drug–drug interactions of drugs, with a focus on the metabolism and transport characteristics of drugs and drug candidates. With a trend of polypills with different mode of action mechanisms and the increased use of medicinal food, the concurrent administration of therapeutic drugs and herbal drugs can cause serious adverse reactions with substrate drugs for drug-metabolizing enzymes and transporters by the inhibition or induction of their activities. Therefore, the prediction and evaluation of the contribution of drug-metabolizing enzymes and transporters to the pharmacokinetics and drug–drug interaction potential of drugs or drug candidates are important in clinics and in the drug development process.

This book serves to highlight pharmacokinetics/drug–drug interactions and mechanistic understanding in relation to drug-metabolizing enzymes and drug transporters.

This book presents a series of drug metabolism and transport mechanisms that govern the pharmacokinetic features of therapeutic drugs, as well as natural herbal medicines. It also deals the pharmacokinetic interaction caused by inhibiting or inducing the metabolic or transport activities under disease states or the coadministration of potential inhibitors. It also deals with microenvironmental pharmacokinetic profiles as well as population pharmacokinetics, which gives new insights regarding the pharmacokinetic features with regard to the drug metabolism and transporters.

> **Im-Sook Song** *Editor*
