Calcium-channel blockers (CCBs) bind to L-type calcium channels in the heart and blood vessels. This decreases calcium entry into cells, leading to effects such as vasodilation, reduced heart rate and contractility, and decreased conduction velocity. CCBs are used to treat hypertension, angina, and arrhythmias by reducing blood pressure, myocardial oxygen demand, and aberrant electrical conduction. There are three classes of CCBs that differ in their selectivity for cardiac versus vascular calcium channels. Dihydropyridines are highly vascular selective, verapamil is relatively cardiac selective, and diltiazem has mixed effects. Side effects vary between classes, with dihydropyridines possibly causing reflex t