Stable isotope techniques offer advantages in safety, sensitivity, specificity, and economy for many types of pharmaceutical investigations when compared to conventional techniques. Nevertheless, pharmaceutical researchers are slow to embrace stable isotope techniques.This book assembles in one place comprehensive reviews of the many applications of stable isotopes and the background material necessary to understand the application. This approach is a deliberate attempt to encourage the usage of stable isotopes in pharmaceutical research. A bonus to the reader is the high standard of contributions from a very talented and diverse group of investigators.