Abstract—From a network medicine perspective, diseases are caused by perturbations in the dynamics of multiple interacting genes - a disease module. A drug that is a suitable candidate for re-purposing, should affect perturbed disease modules other than the one for which it was designed. In other words, it must act on various disease modules. A systematic analysis of re purposing suitability requires deeper understanding of drug target modularity. In this paper, we present a large-scale analysis of drug-target relationships, evaluating the locality of drug targets in protein-protein interaction networks. We show that the various drugs in each category affect different regions in biological networks, and present modular features. Additionally, multiple targets associated to the same drug appear close in the interactome. Our statistical analysis of the functions of the known drug targets reveals that peripheral functions of disease modules, such as signalling, are common targets for many drugs.Sociedad Argentina de Informática e Investigación Operativa (SADIO)