Cardiovascular
Calcium-channel blockers
CCBs — Widely used for blood pressure and angina; some also slow the heart rate.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Calcium-channel blockers are a mainstay for hypertension and angina. They are a particularly common first choice in older patients and in some ethnic groups where they are especially effective.
How it works
They block calcium entry into vascular smooth muscle and heart cells. The dihydropyridines ("-dipine") relax arteries to lower blood pressure; the non-dihydropyridines (verapamil, diltiazem) also reduce heart rate and the force of contraction.
In practice
In practice the class splits in two: the "-dipine" drugs (e.g. amlodipine) mainly relax blood vessels and are a first-line antihypertensive, commonly causing ankle swelling; the rate-limiting agents (diltiazem, verapamil) also slow the heart and are used in angina and some arrhythmias. Avoid combining verapamil or diltiazem with a beta-blocker because of additive heart-rate slowing and the risk of heart block.
Examples
Practical use
How to take it & use it well
- Take it at the same time each day, with or without food, to keep your blood pressure controlled steadily.
- Swallow modified-release tablets whole and do not crush or chew them, as this can release the medicine too fast.
- Avoid grapefruit and grapefruit juice with some of these medicines, as it can raise the drug level and side effects.
- If you miss a dose, take it when you remember the same day, but skip it if it is nearly time for the next one. Do not double up.
- Tell your doctor if you get swollen ankles, flushing, headaches or constipation, as the type or dose may be reviewed.
- Do not stop suddenly without advice, especially if you take it for angina, as this could bring on chest pain.
Common uses
- Hypertension
- Angina
- Rate control in some arrhythmias (rate-limiting agents)
Monitoring
- Blood pressure and heart rate
- Ankle swelling and symptom control
Weighing it up
Advantages & disadvantages
Advantages
- They effectively lower blood pressure and are useful for angina.
- Some types help control certain fast or irregular heart rhythms.
- They are usually taken once a day.
- They do not affect blood sugar or cholesterol.
- They are a good option for many people, including some who cannot take other blood pressure medicines.
Disadvantages
- They commonly cause swollen ankles, flushing and headaches.
- Some types can cause constipation.
- Certain types can slow the heart too much, especially if combined with beta-blockers.
- They can cause dizziness from low blood pressure when starting.
- Some interact with grapefruit and with other heart medicines.
Key safety principles
What to watch for
- Verapamil/diltiazem plus a beta-blocker can cause severe bradycardia or heart block — avoid.
- Verapamil commonly causes constipation; dihydropyridines commonly cause ankle oedema and flushing.
- Caution in significant heart failure with the rate-limiting agents.
Key interactions
What to avoid or check alongside
- Grapefruit and grapefruit juice can raise the level of some of these medicines and increase side effects.
- Combining the rate-slowing types (such as verapamil or diltiazem) with beta-blockers can slow the heart dangerously.
- Taking them with other blood-pressure-lowering medicines can cause your blood pressure to drop too low.
- Some of these drugs can raise the levels of statins, increasing the risk of muscle side effects.
- They can interact with certain medicines processed by the liver, such as some immune-suppressing drugs.
- Alcohol can add to the blood-pressure-lowering effect and dizziness.
Patient & carer advice
- Ankle swelling and flushing are common with amlodipine and not dangerous, but tell us if troublesome
- Avoid grapefruit juice with some of these drugs
- Do not stop a rate-limiting agent abruptly in heart disease
Use with
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Answers
Calcium-channel blockers: frequently asked questions
Why are my ankles swollen?
Ankle swelling is a common side effect, especially with the type used for blood pressure. It is not usually harmful, but tell your GP, as the dose or type can sometimes be changed.
Can I drink grapefruit juice?
With some of these medicines, grapefruit can raise the drug level and increase side effects. Check whether yours is affected, and if so, avoid grapefruit and its juice.
How long until it works?
Blood pressure usually begins to fall within hours to days, with the full effect over a couple of weeks of regular use.
Can I drink alcohol with it?
An occasional drink is usually fine, but alcohol can add to the blood-pressure-lowering effect and cause dizziness, so go carefully.
Is it safe in pregnancy?
Some calcium-channel blockers can be used in pregnancy under medical advice, for example for blood pressure. Tell your doctor if you are pregnant or planning to be so the right choice is made.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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