Sulfaphenazole (Plisulfan) is an inhibitor of CYP2C9 (Ki: 0.3 μM) that demonstrates at least 100-fold selectivity over other CYP450 isoforms (Ki: 63/29 μM for CYP2C8/CYP2C18, respectively, and no activity at CYP1A1, CYP1A2, CYP3A4, CYP2C19). At 10 μM, sulfaphenazole has been shown to inhibit endothelium-derived hyperpolarizing factor synthase, a CYP450 isozyme in the porcine coronary artery homologous to CYP2C8/9 that generates reactive oxygen species in coronary endothelial cells and modulates vascular tone and homeostasis.

CYP2C9:0.3 μM (Ki)