Pharmacology · Calcium channel blockers
Nifedipine !
A dihydropyridine calcium channel blocker that relaxes arteries. The extended-release form is used for high blood pressure and angina.
Updated 2026-11-01
The figure shows nifedipine bound to the rabbit skeletal-muscle L-type channel CaV1.1, which shares the dihydropyridine site with the vascular channel CaV1.2.
Mechanism of action
Nifedipine binds the dihydropyridine site of the L-type calcium channel in arteriolar smooth muscle. Less calcium enters, the arterioles relax and peripheral resistance falls. It has little direct effect on the sinus and AV nodes; a fast fall in blood pressure triggers a sympathetic reflex with tachycardia and flushing, which is why the short-acting form is no longer used for hypertension.
- Nifedipine binds the L-type calcium channel of arterioles
- Less calcium enters and the arterioles relax
- Resistance and blood pressure fall; a fast fall triggers reflex tachycardia
Pharmacokinetics
- Absorption
- Immediate-release forms give a brief peak; extended-release forms smooth it out
- Metabolism
- Liver, by CYP3A4
- Half-life
- About 2 hours, so the extended-release form is used for chronic treatment
Indications
- High blood pressure (extended-release) Arterial hypertension →
- Chronic stable and vasospastic angina Stable angina →
- High blood pressure in pregnancy Preeclampsia →
Adverse effects
Common
- Ankle oedema
- Headache
- Flushing
- Dizziness
- Palpitations and reflex tachycardia
Contraindications
- Known hypersensitivity to nifedipine
Key interactions
- Grapefruit juice
- About doubles nifedipine exposure
- CYP3A4 inducers such as phenytoin or rifampicin
- Much lower nifedipine levels; the combination is avoided
- Strong CYP3A4 inhibitors
- Higher nifedipine levels and hypotension
- Beta blockers
- Useful against reflex tachycardia, but heart failure or hypotension can appear
What is monitored
- Blood pressure and heart rate
- Oedema
- Chest pain when starting
Administration and safety
- Extended-release tablets are swallowed whole, not crushed, chewed or split
- Immediate-release and extended-release forms are different products: the form is checked on every order
- Grapefruit is avoided during treatment
Nursing care
- Check blood pressure and pulse before doses and watch for a sudden drop
- Ask about new chest pain, headache, flushing and ankle swelling
- Explain that an empty tablet shell may appear in the stool and is not a sign that the drug failed
Pregnancy and breastfeeding
With labetalol and methyldopa it is among the antihypertensives used in pregnancy, with reasonable evidence of safety.
Test yourself
Think of the answer, then tap the question to see it.
Why is immediate-release nifedipine avoided for chronic hypertension?
Its brief peak drops blood pressure quickly, triggering reflex tachycardia and possibly angina or infarction.
Which fruit juice doubles nifedipine exposure?
Grapefruit juice, which inhibits intestinal CYP3A4.
Does nifedipine slow AV conduction?
Hardly; as a dihydropyridine it acts mainly on arteries, and heart rate may even rise by reflex.
Related drugs
Related conditions
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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 - NIFEDIPINE tablet, film coated, extended release (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 31 (McGraw Hill, 2023).
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Representative model, for educational purposes only.