ATC Group: C08D Selective calcium channel blockers with direct cardiac effects

Diltiazem is a calcium antagonist. It restricts the slow channel entry of calcium into the cell and so reduces the liberation of calcium from stores in the sarcoplasmic reticulum. This results in a reduction of the amount of available intracellular calcium reducing myocardial oxygen consumption.

Verapamil inhibits the transmembrane influx of calcium ions into the heart and vascular smooth muscle cell. The myocardial oxygen demand is lowered directly as a result of the effect on the energy consuming metabolic processes of the myocardial cell and indirectly due to a reduction of the afterload. Due to its effect on coronary vascular smooth muscle, verapamil enhances myocardial blood flow, even in post‐stenotic areas, and relieves coronary spasms. These properties contribute to the anti‐ischaemic and antianginal efficacy of verapamil in all types of coronary artery disease.