An overview of adverse drug reactions.

An enormous number of drugs are introduced to the market every year and practically it is not feasible to avoid potential drug interactions. These drug interactions can lead to altered systemic exposure, resulting in disparities in drug response of the other co-administered drugs. Additionally, associated ingestion of dietary supplements, citrus fruit/juice could also change systemic exposure of drugs, thus leading to Adverse Drug Reactions (ADRs). In 1972, World Health Organization (WHO) defined ADR as ‘a response to a drug which is noxious and unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis, or therapy of disease, or for the modifications of physiological function’. Multiple drug courses for therapy carry the risk of adverse interactions, which may result to loss of efficacy. Therefore, it is crucial to assess potential drug interactions and risk-benefit analysis prior to market approval as well as during the post-marketing period.