“…3 –5 This difficulty results from the need to initially recognize potential clinically significant toxicities (ie, AEs) reported as clinical signs, symptoms, or medical concepts and evaluate these AEs as consequences of a DDI. 3,4,6 The identification of DDIs between an established older drug and a newly approved product is particularly challenging because unless these older products are the representative drug probe for a particular drug class or a particular type of interaction (ie, ketoconazole or ritonavir representing CYP3A4 inhibitors and rifampin representing CYP3A4 inducers), additional PK simulation models and studies are not conducted to evaluate DDIs with newly authorized drug products. Drug manufacturers have to rely on reports of potential DDI-related toxicities from their postmarketing surveillance of postmarketing safety data, including those reported in the published literature, to recognize and evaluate new DDIs.…”