This paper uses a recent approach toward drug discovery, in which in silico tools and experimental data are combined together to study the structural features of amlodipine and their relevance in the peculiar pharmacodynamic and pharmacokinetic profiles of this long acting calcium antagonist. Results reveal for amlodipine two families of conformers (folded and extended) but also demonstrate that protonation is-the predominant factor governing amlodipine intermolecular interactions among which ionic forces play a major role. (C) 2004 Elsevier Ltd. All rights reserved.