Amlodipine vs nifedipine.
Two drugs from the same subclass with the same target can behave very differently, and this pair is the cleanest illustration of why pharmacokinetics is not a footnote to pharmacology. Nothing about the receptor differs here. Only the speed does.
Both are dihydropyridine calcium channel blockers acting on vascular smooth muscle, and the difference is entirely how fast they act. Amlodipine has a half-life of around 35 to 50 hours, so blood pressure falls gradually; immediate-release nifedipine acts fast enough to trigger reflex tachycardia.
Amlodipine vs Nifedipine at a glance
| Property | Amlodipine | Nifedipine |
|---|---|---|
| Subclass | Dihydropyridine | Dihydropyridine |
| Main site | Vascular smooth muscle | Vascular smooth muscle |
| Half-life | About 35 to 50 hours | Short for immediate release; longer for modified release |
| Onset | Gradual | Rapid in immediate-release form |
| Reflex tachycardia | Minimal | Marked with immediate release |
| Dosing | Once daily | Modified release once or twice daily |
Why speed causes reflex tachycardia
Baroreceptors respond to the rate of change in blood pressure as well as its level. A rapid fall is read as an emergency and triggers a sympathetic surge, raising heart rate and myocardial oxygen demand. A gradual fall of the same magnitude does not. Amlodipine avoids reflex tachycardia by being slow, not by being different at the receptor.
Why immediate-release nifedipine was abandoned in hypertension
The sympathetic surge described above is not merely uncomfortable. In patients with coronary disease, raising heart rate and contractility while dropping perfusion pressure is exactly the wrong combination, and short-acting nifedipine was associated with harm in that setting. Modified-release formulations slow the onset and largely remove the problem, which is why the formulation matters more than the molecule.
Why both cause ankle oedema
Dihydropyridines dilate arterioles far more than venules, so capillary hydrostatic pressure rises and fluid is pushed into the tissue. Because total body fluid is normal, the oedema responds poorly to diuretics, which is the clinical clue distinguishing it from heart failure. This is a class effect and does not separate the two drugs.
Which one would the question pick?
Exams rarely ask what a drug does. They describe a patient and ask which of the two you would choose, so the scenarios below matter more than either drug monograph.
| Scenario | Pick | Why |
|---|---|---|
| Routine hypertension | Amlodipine | Long half-life gives smooth control and once daily dosing. |
| Raynaud phenomenon | Either | Both are effective; amlodipine is better tolerated. |
| Missed doses likely | Amlodipine | A half-life measured in days is forgiving of a missed dose. |
Traps that catch people on this pair
Blaming ankle oedema on fluid overload
The oedema is caused by arteriolar dilation raising capillary pressure, not by fluid retention, and adding a diuretic rarely helps.
Ignoring the formulation
Immediate-release and modified-release nifedipine behave so differently that they are effectively different drugs in practice.
Common questions
What is the difference between amlodipine and nifedipine?
Both are dihydropyridine calcium channel blockers acting on vascular smooth muscle, and the difference is entirely how fast they act. Amlodipine has a half-life of around 35 to 50 hours, so blood pressure falls gradually; immediate-release nifedipine acts fast enough to trigger reflex tachycardia.
What is the difference between amlodipine and nifedipine?
Both are dihydropyridine calcium channel blockers with the same target. Amlodipine has a much longer half-life, so blood pressure falls gradually, while immediate-release nifedipine acts quickly enough to provoke reflex tachycardia.
Why does amlodipine cause ankle swelling?
It dilates arterioles much more than venules, raising capillary hydrostatic pressure so fluid moves into the tissue. Total body fluid is normal, which is why diuretics help little.
Why is short-acting nifedipine avoided in hypertension?
Its rapid onset triggers a baroreceptor-mediated sympathetic surge, raising heart rate and myocardial oxygen demand, which is hazardous in coronary disease.
Go deeper on the mechanism
A comparison only sticks once the shared mechanism underneath it does, because what separates two drugs is always a variation on something they have in common.
- Diuretics — the class both drugs belong to
- Cardiovascular pharmacology questions — test the distinction under time
- CYP450 inducers and inhibitors
Other comparisons
Heparin vs Warfarin · Warfarin vs DOACs · Unfractionated heparin vs Enoxaparin · Propranolol vs Atenolol · Metoprolol vs Atenolol · Furosemide vs Bendroflumethiazide · Spironolactone vs Eplerenone · Simvastatin vs Atorvastatin · All comparisons
Study aid only. This page is written for learning and examination practice. It is not medical advice, not clinical decision support, and must never be used to make a decision about a real patient. Always verify against your local formulary, the product literature and a qualified pharmacist. See our medical disclaimer.
Two drugs, one property apart.
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