Abstract
This chapter provides an overview of the physiologic and pharmacokinetic changes that influence drug disposition during pregnancy. The dynamic regulation of hepatic phases I and II metabolic enzymes as well as transporters in pregnant animals and women is reviewed. Attention is also placed upon the role of individual hormones, such as estradiol and progesterone, as well as nuclear receptors in the adaptive changes in enzyme and transporter levels that occur during pregnancy. A comprehensive case study explores the coordinated regulation of metabolic enzymes, transporters, and nuclear receptors that control bile acid homeostasis in pregnant rodents. Understanding how pregnancy alters endobiotic and xenobiotic disposition is critical to ensure optimal management of diseases.