ACT-709478 (Compound 66b) blocks Cav3.1, Cav3.2, Cav3.3, Cav1.2 with IC50s of 6.4, 18, 7.5 and 2410 nM, respectively. ACT-709478 blocks recombinant channel hCav3.3 potently with marked voltage-dependency (Kr≈1500 nM and Ki≈20 nM). ACT-709478 blocks currents through hKv11.1-hERG channels with an IC50 of 5.5 μM.
ACT-709478 also inhibits P450 enzymes with IC50s of 14, 15, 22, 25, 51 and 52 μM for CYP2C8,CYP2D6 CYP2C9, CYP2C19, CYP3A4, and CYP2B6, respectively.