**1. Introduction**

This chapter introduces biochemical pharmacology and highlights drug absorption and drug transformation reactions and a general introduction to pharmacology, drug discovery and clinical trials for new drug candidates. It also introduces the concept of individualization of drug therapies. After studying this chapter, one is expected to demonstrate understanding the following: (i) Linkage between the various pharmacological processes (ii) Routes of drug administration, (iii) Mechanisms of drug absorption (iv) The kinetics of drug disposition and concepts, such as volume of distribution, initial dose and half-life, (v) The biotransformation and excretion of drugs.(vi) The role of biochemical knowledge in the discovery and develop‐ ment of candidate drug compounds into useful drugs (vii) Basic design of clinical trials of new drugs and the drug approval process.(viii) The linkage between genetic variations and varied drug responses in different individuals (ix) The various adverse drug reactions in different patients (x) How different dosage regimens are calculated with respect to the prevailing health status of individuals and how adjustments are carried out in old patients or geriatrics.
