Pharmacy PEBC Practice Exam

Calcium channel blockers function by preventing calcium from entering the cells of the heart and blood vessels, which is central to their therapeutic effects. Calcium is crucial for various cellular functions, including muscle contraction. In the heart, calcium entry is essential for the contraction of heart muscle cells (myocytes), and in blood vessels, it facilitates the contraction of smooth muscle leading to vasoconstriction.

When calcium channel blockers are used, they inhibit this calcium influx, leading to a reduction in cardiac contractility and heart rate, as well as vasodilation (relaxation of blood vessels). This mechanism results in lowered blood pressure and decreased cardiac workload, thereby benefiting conditions such as hypertension and angina.

The other options describe functions that are not related to the mechanism of calcium channel blockers. For instance, some increase heart rate and contractility, which is contrary to what calcium channel blockers do. Others, such as serotonin reuptake inhibition or insulin production stimulation, pertain to entirely different drug classes and mechanisms unrelated to calcium channels. Understanding the precise role of calcium channel blockers as agents that modulate calcium entry at the cellular level is essential for applying this knowledge in clinical scenarios.