For example, in LePendu et al. [2013], “Rofecoxib 12.5 mg oral tablet”and “Vioxx” are normalized to the active ingredient rofecoxib using the relationships from RxNorm.12 Finally, in some approaches, the timestamps in the EHRs are used to induce a temporal ordering over the recognized concepts for each patient [LePendu et al. 2013].