Thrombin-inhibitor X-ray crystal structures, in combination with the installation of binding elements optimized within the pyrazinone series of thrombin inhibitors, were utilized to transform a weak triazolopyrimidine lead into a series of potent oxazolopyridines. A modification intended to attenuate plasma protein binding (i.e., conversion of the P3 pyridine to a piperidine) conferred significant factor Xa activity to this series. Ultimately, these dual thrombin/factor Xa inhibitors demonstrated excellent in vitro and in vivo anticoagulant efficacy.