Ivabradine is a highly selective open channel blocker that targets the mixed Na+/K+ inward “funny current” (If) carried by hyperpolarization-activated cyclic nucleotide gated (HCN) channels. It suppresses channel activity at HCN1, HCN2, and HCN4, all with the same EC50 value of 4 μM. Notably, ivabradine selectively targets cardiac signaling, resulting in resting heart rate reducing (bradycardic) effects.
