Ivabradine reduces heart rate by a mechanism different from beta-blockers. It acts by:

• A Blocking L-type calcium channels in the SA node
• B Inhibiting the funny (If) current (HCN channels) in the SA node ✓
• C Activating muscarinic M2 receptors in the SA node
• D Blocking beta-1 adrenoceptors only in the SA node

Explanation

Ivabradine selectively inhibits the hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels responsible for the If (funny) current in SA nodal pacemaker cells. This current drives the slow diastolic depolarization that determines heart rate. Unlike beta-blockers, ivabradine has no effect on myocardial contractility or blood pressure. It is used in stable angina (when beta-blockers are contraindicated) and in symptomatic heart failure with reduced EF.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.