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Calcium Channel Blockers

Calcium Channel Blockers: Mechanisms & side effects Authors: Caroline Kokorudz Reviewers: Rafael Sanguinetti Andrew Wu Luiza Radu Timothy Pollak* * MD at time of publication Calcium channel blocker medications inhibit Ca2+ channels in smooth muscle Reduction of Ca2+ influx into smooth muscle cells Inhibits calcium-dependent aldosterone synthesis reducing Na+ & H2O resorption in renal distal tubules Negative feedback to pituitary gland causing ↑ ACTH (adrenocorticotropic hormone) ↑ Androgens (testosterone) Testosterone acts on gingival cells (multiple cell types that support teeth) & connective tissue matrix Gingival hyperplasia (gum overgrowth) Non-dihydropyridines: (Phenylalkylamines [verapamil], Benzothiazepines [diltiazem]) less potent vasodilators & selective for heart muscle Prevents smooth muscle contraction Dihydropyridines: (amlodipine, felodipine, nifedipine) vasodilate vascular smooth muscle ↓ Arterial resistance and blood pressure in coronary & peripheral arteries Coronary artery vasodilation ↓ Pressure in coronary arteries ↑ Blood flow through coronary arteries Reduced ischemia relieves angina Inhibits L-type Ca2+ channels, preventing rapid nodal depolarization Reduces excitation of sinoatrial (SA) & atrioventricular (AV) nodal tissues ↓ Conduction speed of electrical impulses ↓ Contractile strength of cardiomyocytes (heart muscle cell) ↓ Systemic vascular resistance & cardiac afterload (heart pumping resistance) ↑ Blood volume flowing into significantly smaller vessels ↑ Capillary blood pressure ↑ Circulation to face Flushes (red & warm) ↓ Cardiac output ↓ Tissue perfusion & attempt to ↑ cardiac output Worsens heart failure ↓ Oxygen demand of heart muscle More favorable oxygen supply to demand ratio Relieves angina ↓ Blood pressure ↓ Cerebral perfusion Syncope (fainting) Relieves angina Capillary fluid leak increased to interstitial space Peripheral edema ↑ Intracranial pressure Compresses nerve endings Headache ↓ Heart rate Bradycardia Suppresses dysrhythmias (abnormal heart rhythm) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Nov 21, 2024 on www.thecalgaryguide.com