Abstract
The disposition of organic cations in the liver and kidneys are under a dynamic regulation by the endocrine and metabolic systems of the body. Researchers have demonstrated the ability of steroids, sex hormones, and physiological states such as pregnancy to alter the expresion and function of transporter proteins that mediate the uptake and efflux of organic cations. This chapter reviews the endocrine and metabolic pathways that influence the pharmacokinetics as well as the toxicity of organic cations.