Drugs usually act on either cellular or genetic chemicals in the body, known as targets, which are believed to be associated with specific diseases. Scientists use a variety of techniques to identify and isolate these individual targets to learn more about their functions and how they influence disease. Compounds are then identified that have various interactions with those drug targets which might be helpful in treatment of that specific disease.

In order to select targets most likely to be useful in the development of new treatments, researchers analyze and compare each drug target to others based on their association with a specific disease and their ability to regulate biological and chemical compounds in the body. Tests are conducted to confirm that interactions with the drug target are associated with a desired change in the behavior of diseased cells. Research scientists can then identify compounds that have an effect on the target selected.

A lead compound or substance is one that is believed to have potential to treat disease. Laboratory scientists can compare known substances with new compounds to determine their likelihood of success. Leads are sometimes developed as collections, or libraries of individual molecules that possess properties needed in a new drug. Testing is then done on each of these molecules to confirm its effect on the drug target.

Lead optimization compares the properties of various lead compounds and provides information to help biopharmaceutical companies select the compounds with the greatest potential to be developed into safe and effective medicines. Lead prioritization studies are then conducted in living organisms (in vivo) and in cells in the test tube (in vitro) to gauge how they are metabolized by the body, and thereafter how they affect the body’s ability to fight the disease.