The process of discovering chemical entities with the potential to become therapeutic agents is known as drug discovery. All activities involved in transforming a molecule from a drug candidate (the end-product of the discovery phase) to a product licensed for marketing by the competent regulatory authorities are referred to as drug development. The identification of new molecular entities that may be useful in the treatment of diseases that qualify as unmet medical needs is a key goal of drug development programs.
Drug screening is the process of identifying and optimizing potential drugs prior to the selection of a candidate drug for clinical trials. A broad range of analytical assays are used in bioactive compound screening to determine the potential of biological extracts or molecules. The assays might be done on the whole animal, in cells, or at the molecular level. Classic pharmacology, also known as phenotypic drug discovery, which is the historical basis of drug discovery, and reverse pharmacology, or target-based drug discovery, are two complementary approaches to drug discovery.