Abstract
Tools of Drug Development Drug development is the foremost objective of most pharmacologists in the pharmaceutical companies and some pharmacologists in the other research institutions. To meet this objective, thousands of new chemical compounds must be evaluated in order to discover one which can be safely employed in the treatment of human illness. Such evaluation requires an enormous number of experimental subjects specially prepared for this purpose. Since use of human patients for initial screening of new chemicals is not feasible one must depend on laboratory animals that can be used repeatedly and extensively.