Stability of drug is the capacity of the pharmaceutical dosage form to maintain the chemical, physical, microbial and therapeutic properties during the time of storage and usage by the patient. Stability studies are done to determine the expiry date of products and to choose formulations and container closure techniques that are appropriate in terms of stability in order to assess storage needs and shelf life. There are various types of stability studies which we can consider to determine shelf life of pharmaceutical products like Physical stability, Chemical stability and microbiological stability. All of these are important but among them Chemical stability is more important as changes in chemical structure leads to loss of therapeutic activity of drug