Zatebradine hydrochloride is a bradycardic agent that creates use-dependent inhibition of hyperpolarization-activated current (If) in sinoatrial node cells (EC50 = 480 nM) and Purkinje fibres.

Zatebradine(UL-FS49) is a potent HCN channels antagonist, which decreased the heartbeat in a reversible manner; 92% inhibition of the hHCN1-mediated current at 10 uM.

HCN4 inhibitor EC18 (EC18) is a HCN4-prefering blocker.

NUCC-0200590 is a small-molecule inhibitor of the TRIP8b-HCN interaction with IC50 of 7.0 uM in AlphaScreen assays, effectively disrupts the TRIP8b-HCN interaction in vitro and in vivo.

Org 34167 is a broad-spectrum inhibitor of HCN channels with IC50 of 23.4, 8.2 and 9.2 uM for HCN1, HCN2 and HCN4 channels, respectively, slowing activation and causing a hyperpolarising shift in voltage-dependence of activation.

RO-275 is a potent, selective HCN1 ion channel inhibitor with IC50 of 46 nM, displays 311/100/302-fold selectivity over HCN2/HCN3/HCN4.