Lopressor is a dihydropyridine calcium antagonist, a CCB class antihypertensive drug, and the drug name is amlodipine benzoate. It inhibits the entry of calcium ions across the membrane into vascular smooth muscle and cardiac muscle. The contraction process of cardiac muscle and vascular smooth muscle depends on the entry of extracellular calcium ions into the cell through ion channels, and amlodipine can selectively inhibit calcium ion transport across the membrane. However, amlodipine does not affect serum calcium concentrations. Amlodipine is a peripheral arterial vasodilator and acts directly on smooth muscle cells of blood vessels, thereby reducing peripheral vascular resistance and blood pressure.