In all of life that is relevant to disease, there are hundreds of thousands of proteins. Every drug compound binds in varying degrees to many different proteins, and can affect very many proteins in other ways, such as through changing their expression, or phosphorylation state. The huge variety of possible protein targets, and the large variety of patterns of possible effects on proteins create an enormous range of possible interactions between a drug molecule and any biological system. For this fundamental reason, the biological effects of a molecule's interactions with pathogenic, pathological and normal cells have been very difficult to predict.
Based on advances in chemical biology and network science, network pharmacology is a distinctive new approach to drug discovery. It involves application of network analysis to determine the set of proteins most critical in any disease, and then chemical biology to identify molecules capable of targeting that set of proteins. By addressing the true complexity of disease and by seeking to harness the ability of drugs to influence many different proteins, network pharmacology differs from conventional drug discovery approaches, which have generally been based on highly specific targeting of a single protein. Network pharmacology has the potential to provide new treatments for complex diseases where conventional approaches have failed to deliver satisfactory therapies.