Calcium Channel Blockers

Calcium channel blockers (CCBs) inhibit L-type calcium channels. That shared mechanism does not make every CCB clinically interchangeable. The first group is the dihydropyridines, including amlodipine and nifedipine. Their dominant action is arteriolar relaxation. Systemic vascular resistance falls, so blood pressure and afterload fall. Their effects on the sinoatrial (SA) and atrioventricular (AV) nodes are comparatively limited. The second group is the non-dihydropyridines: diltiazem and verapamil. They also relax vascular smooth muscle, but they significantly slow AV-node conduction and reduce myocardial contractility. That makes them useful for selected ventricular-rate problems, but potentially dangerous in bradycardia, conduction disease, or impaired left-ventricular function. For an NCLEX-RN question, do not begin with the drug name alone. Begin with the patient's physiology: - Is the therapeutic problem high vascular resistance, myocardial oxygen demand, or excessive ventricular rate? - Is the pulse adequate? - Is conduction intact? - Is the ventricle strong enough to tolerate a negative inotrope? - Is the patient perfusing, or are dizziness, syncope, pulmonary congestion, or shock developing? The safe choice is the one that connects the subclass to the patient's...