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Amlodipine — sold as Norvasc — is one of the most widely prescribed calcium channel blockers (CCBs) in the world. It belongs to the dihydropyridine class and works by relaxing the smooth muscle in arterial walls, lowering peripheral vascular resistance and blood pressure. It is used to treat hypertension and stable angina, and is taken once daily. Amlodipine is notable for having one of the longest half-lives of any commonly prescribed cardiovascular medication.
How Long Does Amlodipine Stay in Your System?
Amlodipine has a plasma half-life of approximately 35–50 hours, with an average of around 40 hours in healthy adults. This makes it one of the longest-acting antihypertensive drugs available. After a single dose, it takes approximately 7–10 days (5 half-lives, ~200 hours) to be fully cleared from the body.
With once-daily dosing, amlodipine reaches a steady state — where the amount entering the body each day equals the amount eliminated — after approximately 7–8 days. It is at steady state that amlodipine provides its optimal, stable blood pressure control. This also means that when starting amlodipine, the full blood pressure-lowering effect may not be apparent for 1–2 weeks.
Amlodipine is extensively metabolised in the liver (primarily by CYP3A4) into inactive metabolites, which are then excreted in the urine. Unlike lisinopril, amlodipine has no active metabolites — so its pharmacodynamic effect tracks closely with the plasma concentration of the parent drug.
Why Is Amlodipine's Long Half-Life Clinically Advantageous?
The exceptionally long half-life of amlodipine provides several significant clinical advantages:
- Smooth blood pressure control — Because plasma levels change very slowly, amlodipine produces gradual, sustained blood pressure reduction without the sharp peaks and troughs seen with shorter-acting calcium channel blockers.
- Minimal rebound on missed doses — A missed dose causes only a modest ~10–15% drop in plasma levels, meaning blood pressure control is largely maintained even if a single dose is forgotten.
- No abrupt rebound hypertension — Unlike some antihypertensives, stopping amlodipine does not cause dangerous rebound effects. Blood pressure rises gradually over several days as the drug slowly clears.
- Reduced reflex tachycardia — Compared to shorter-acting dihydropyridines like nifedipine, amlodipine's slow onset means the vasodilation is gradual, triggering less compensatory heart rate increase.
What Affects How Long Amlodipine Stays in Your System?
- Age — Elderly patients (65+) clear amlodipine significantly more slowly. The half-life extends to approximately 65 hours in older adults, compared to 40 hours in younger patients. Lower starting doses (2.5mg) are typically recommended for elderly patients.
- Liver function — Amlodipine is extensively metabolised by the liver. In patients with severe hepatic impairment, the half-life can extend to 60 hours or more, and lower doses are required. A titration of 2.5mg starting dose is recommended in hepatic impairment.
- CYP3A4 inhibitors — Drugs that inhibit CYP3A4 (including ketoconazole, itraconazole, clarithromycin, HIV protease inhibitors, and grapefruit juice) can increase amlodipine plasma levels and prolong its effective duration.
- Sex — Women tend to have slightly higher amlodipine plasma concentrations than men at the same dose, though standard dosing is not differentiated by sex.
- Kidney function — Unlike lisinopril, amlodipine clearance is not significantly affected by kidney function, as it is hepatically metabolised rather than renally excreted.
What Happens If I Miss a Dose of Amlodipine?
Because amlodipine has a half-life of 35–50 hours, missing a single daily dose has minimal impact on overall blood pressure control. Plasma levels drop by only approximately 10–15% over 24 hours, which is unlikely to cause a clinically significant rise in blood pressure for most patients.
If you miss a dose, take it as soon as you remember on the same day. If it is the next day, skip the missed dose and resume your normal once-daily schedule. Do not double up. Consistent daily dosing is important for maintaining the stable steady-state levels that provide optimal blood pressure and angina control.
Amlodipine stands out from other calcium channel blockers because of its unusually long elimination half-life of roughly 30–50 hours — far longer than nifedipine or diltiazem. This long half-life, together with a gradual onset of action, allows reliable once-daily dosing and produces a smooth, sustained blood-pressure effect without the reflex tachycardia that shorter-acting dihydropyridines can cause. Steady-state plasma concentrations are typically reached after 7–8 days of continuous daily dosing. Amlodipine is extensively metabolised by the liver (mainly via CYP3A4) to inactive metabolites, and dose adjustment is generally not required for kidney impairment — points emphasised in the FDA-approved prescribing information and the U.K. NHS / electronic Medicines Compendium summary of product characteristics.
Sources cross-checked: U.S. FDA prescribing information (DailyMed), U.K. NHS medicines information, and additional official references from the European Medicines Agency, NIH MedlinePlus / LiverTox, the WHO Model List of Essential Medicines, or the American Thyroid Association, depending on the medication. This page is general educational information only and is not medical advice.