We, the human beings, to quench his thirst of comfort-ability in life are in the rat race to destroy the environment which in turn is a great deal to the pharmaceutical companies. The medicines they produce reacts with other chemical reagents to degrade to final product. This book conveys the rate at which they degrade with respect to their concentration, temperature and pressure they withstand and various other factors influencing some of the chosen pharmaceutical agent are being discussed. With the process, while they reach the final product they should have undergone vast complex reactions which is in detail understood under the heading mechanism, with graphical explanations.