AEMCA Practice Exam

What is the mechanism of action of diltiazem (Cardizem)?

1. Inhibition of serotonin receptors

2. Blockade of calcium channels

3. Agonism of beta-adrenergic receptors

4. Inhibition of sodium channels

The correct answer is: Blockade of calcium channels

Diltiazem, commonly known as Cardizem, primarily functions through the blockade of calcium channels. This mechanism is crucial for its therapeutic effects, particularly in the management of hypertension and certain types of cardiac arrhythmias. By inhibiting the influx of calcium ions into cardiac and vascular smooth muscle cells, diltiazem leads to a decrease in intracellular calcium concentration. This reduction causes relaxation of the vascular smooth muscle, resulting in vasodilation and subsequently lowering blood pressure. Additionally, this calcium channel blockade has implications for the heart as well. It reduces the force of contraction (negative inotropic effect) and lowers the heart rate (negative chronotropic effect) by suppressing conduction through the atrioventricular (AV) node. These combined effects make diltiazem effective in managing conditions like angina and controlling the heart rate in atrial fibrillation. The other mechanisms listed, such as inhibition of serotonin receptors or agonism of beta-adrenergic receptors, do not pertain to the action of diltiazem. Instead, they relate to entirely different classes of drugs, which serve different therapeutic purposes. Similarly, inhibition of sodium channels does not characterize diltiazem’s mechanism of action but is relevant to other medication classes,