Pharmacology · Class
Calcium channel blockers !
Medicines that block L-type calcium channels, so arteries relax and, with some members, the heart beats slower and with less force.
Updated 2026-11-01
What they are
Blockers of the L-type voltage-gated calcium channel, used for high blood pressure, angina, some supraventricular arrhythmias and, in special cases, vasospasm after subarachnoid haemorrhage. There are two big groups: dihydropyridines (amlodipine, nifedipine), which act mainly on arteries, and non-dihydropyridines (verapamil, diltiazem), which also slow the sinus node and the AV node.
Mechanism of action
Calcium entering through L-type channels triggers contraction in vascular smooth muscle and heart muscle and drives the pacemaker current of the sinus and AV nodes. Blocking the channel relaxes arterioles (lower afterload, less coronary spasm). Verapamil and diltiazem also depress contractility and slow conduction through the AV node; dihydropyridines barely do, and their vasodilation may trigger a reflex tachycardia.
Target: L-type voltage-gated calcium channel (CaV1.2, α1C subunit)
Drugs in this class
- AmlodipineA long-acting calcium channel blocker that relaxes arteries. Used for high blood pressure and angina; ankle swelling…L-type voltage-gated calcium channel (CaV1.2)
- DiltiazemA calcium channel blocker that acts on both the heart and the arteries. Used for angina, high blood pressure and rate…L-type voltage-gated calcium channel (CaV1.2)
- NifedipineA dihydropyridine calcium channel blocker that relaxes arteries. The extended-release form is used for high blood…L-type voltage-gated calcium channel (CaV1.2)
- VerapamilA calcium channel blocker that acts mostly on the heart: it slows the AV node. Used for angina, high blood pressure…L-type voltage-gated calcium channel (CaV1.2)
- NicardipineA dihydropyridine given by continuous IV infusion to lower blood pressure in a controlled way when oral treatment is…L-type voltage-gated calcium channel (CaV1.2)
- NimodipineA lipid-soluble dihydropyridine given by mouth after subarachnoid haemorrhage to reduce damage from delayed ischaemia…L-type voltage-gated calcium channel (CaV1.2)
Others in the class
- Felodipine
- Lercanidipine
- Isradipine
Test yourself
Think of the answer, then tap the question to see it.
What is the key difference between dihydropyridine and non-dihydropyridine calcium channel blockers?
Dihydropyridines act mainly on arterial smooth muscle. Verapamil and diltiazem also slow the sinus and AV nodes and depress contractility.
Why does amlodipine cause ankle oedema that does not respond well to diuretics?
It dilates the precapillary arterioles more than the venules, raising capillary pressure; it is not salt and water retention.
Which calcium channel blockers are avoided in a patient already on an intravenous beta blocker, and why?
Verapamil and diltiazem: together with a beta blocker they can cause severe bradycardia, AV block and low output.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - AMLODIPINE BESYLATE tablet (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - VERAPAMIL HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.