Pharmacology  ·  Cardiovascular

Calcium Channel Blockers in Angina — Two Subclasses, Two Profiles

L-type channel mechanism, tissue selectivity, combination rules, and subclass-specific adverse effects

• All calcium channel blockers block voltage-gated L-type calcium channels, but tissue selectivity divides the class: dihydropyridines are highly vascular-selective, producing peripheral and coronary vasodilation with minimal cardiac rate or conduction effect; non-dihydropyridines act on both vascular and cardiac tissue, adding heart rate slowing and atrioventricular nodal suppression.
• Amlodipine is the preferred dihydropyridine for chronic angina — its slow channel binding produces gradual vasodilation that avoids the reflex tachycardia triggered by faster-acting agents such as immediate-release nifedipine.
• Non-dihydropyridines are first-line for vasospastic angina alongside nitrates; because they also slow heart rate, they can serve as beta-blocker substitutes when beta-blockers are contraindicated.
• Combining a beta-blocker with a dihydropyridine is preferred — the beta-blocker blunts the reflex tachycardia and no additive conduction depression occurs; combining a beta-blocker with a non-dihydropyridine is contraindicated because both classes independently suppress sinoatrial and atrioventricular nodal conduction, risking severe bradycardia or complete heart block.
• Peripheral edema (ankle) is the most common dihydropyridine adverse effect, caused by arteriolar dilation without matching venodilation — it does not respond to diuretics; non-dihydropyridines are contraindicated in heart failure with reduced ejection fraction due to negative inotropy, while amlodipine is safe in that population.