How do calcium channel blockers work and what are the two main types?

Calcium channel blockers prevent calcium from entering smooth muscle cells of blood vessels and cardiac muscle, causing vasodilation and reducing blood pressure. The two main types are dihydropyridines and nondihydropyridines. Dihydropyridines like amlodipine and nifedipine primarily relax blood vessels with minimal heart rate effect, identified by the suffix "dipine." Nondihydropyridines like verapamil and diltiazem also slow heart rate and reduce cardiac contractility, making them useful for arrhythmias.