Amlodipine (Norvasc)
amlodipine besylate
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Hypertension | Adults; Pediatric ≥6 years | Monotherapy or combination | FDA Approved |
| Chronic stable angina | Adults | Monotherapy or combination with other antianginals | FDA Approved |
| Vasospastic angina (Prinzmetal or variant) | Adults | Monotherapy or combination | FDA Approved |
| Angiographically documented CAD (without HF or EF <40%) | Adults | Reduces hospitalization for angina and revascularization risk | FDA Approved |
Amlodipine is a first-line antihypertensive with robust outcome data from large trials including ALLHAT and ASCOT-BPLA, demonstrating cardiovascular event reduction comparable to other major antihypertensive classes. In the CAMELOT trial, amlodipine reduced composite cardiovascular endpoints by 31% compared with placebo in patients with angiographically documented coronary artery disease. The drug is particularly well-suited for patients with concurrent hypertension and angina given its dual mechanism of afterload reduction and coronary vasodilation.
Raynaud phenomenon — Amlodipine reduces attack frequency and severity through peripheral vasodilation. Calcium channel blockers are considered first-line pharmacotherapy for primary Raynaud disease. (Evidence: Moderate — meta-analysis of CCBs in Raynaud)
Migraine prophylaxis — Case reports and small series suggest reduced migraine frequency with amlodipine 5–10 mg daily, though large controlled trials are lacking. Not considered first-line. (Evidence: Low — case reports/series)
Pediatric pulmonary hypertension — May be considered in children with positive acute vasoreactivity testing per AHA/ATS guidelines; dosing should be titrated from a low starting dose. (Evidence: Low — guideline recommendation with limited data)
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Hypertension — standard adult | 5 mg once daily | 5–10 mg once daily | 10 mg/day | Titrate over 7–14 days based on BP response May take with or without food at any time of day |
| Hypertension — elderly, small, or fragile patient | 2.5 mg once daily | 2.5–10 mg once daily | 10 mg/day | Reduced clearance in elderly (AUC increased ~40–60%) Also start at 2.5 mg when adding to existing antihypertensive regimen |
| Hypertension — hepatic insufficiency | 2.5 mg once daily | 2.5–5 mg once daily | 10 mg/day | Half-life extends to ~56 h; titrate slowly with close BP monitoring AUC increases ~40–60% in hepatic impairment |
| Chronic stable angina — symptom control | 5 mg once daily | 10 mg once daily | 10 mg/day | Most patients require 10 mg for adequate effect Can combine with beta-blockers, nitrates |
| Vasospastic (Prinzmetal) angina | 5 mg once daily | 5–10 mg once daily | 10 mg/day | Lower dose in elderly or hepatic impairment Blocks coronary spasm via direct vascular smooth muscle relaxation |
| Documented CAD — cardiovascular risk reduction | 5 mg once daily | 5–10 mg once daily | 10 mg/day | Majority of CAMELOT trial patients required 10 mg Indicated in CAD patients without HF or EF <40% |
Pediatric Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Hypertension — ages 6–17 years | 2.5 mg once daily | 2.5–5 mg once daily | 5 mg/day | Doses >5 mg/day have not been studied in pediatric patients Effect in children <6 years not established |
Amlodipine’s long half-life means that steady-state plasma levels are not reached until 7–8 days of consecutive daily dosing. Allow 7–14 days between dose titration steps to assess the full blood pressure effect. The gradual onset of action also makes acute hypotensive episodes unlikely, which is a clinical advantage over shorter-acting dihydropyridines. Upon discontinuation, blood pressure returns to baseline slowly over 7–10 days with no rebound hypertension.
Pharmacology
Mechanism of Action
Amlodipine is a third-generation dihydropyridine that selectively inhibits voltage-dependent L-type calcium channels in vascular smooth muscle and, to a lesser extent, cardiac muscle. By blocking calcium influx through these channels, it reduces intracellular calcium availability, leading to relaxation of arterial smooth muscle and peripheral vasodilation. The net effect is a reduction in peripheral vascular resistance and blood pressure without clinically significant negative inotropy at therapeutic doses. Amlodipine is an ionized compound at physiological pH (pKa = 8.6), which gives it a uniquely gradual rate of association with and dissociation from the calcium channel receptor. This slow binding kinetics underlies its long duration of action and smooth 24-hour blood pressure control with minimal peak-to-trough fluctuation. In angina, amlodipine reduces myocardial oxygen demand by decreasing afterload and directly relieves coronary vasospasm by relaxing coronary artery smooth muscle.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Bioavailability 64–90%; Tmax 6–12 h; well absorbed (~96%); food does not affect absorption | Once-daily dosing is sufficient; can be taken with or without meals; gradual absorption contributes to smooth onset |
| Distribution | Vd ~21 L/kg; protein binding ~93%; crosses placenta | Large volume of distribution reflects extensive tissue binding; hemodialysis is ineffective in overdose due to high protein binding |
| Metabolism | Extensively hepatic (~90%) via CYP3A4/3A5 to inactive metabolites; no significant first-pass metabolism | Dose reduction needed in hepatic impairment; susceptible to strong CYP3A4 inhibitors increasing exposure; CYP3A4 inducers may reduce efficacy |
| Elimination | Terminal t½ 30–50 h; 10% excreted unchanged in urine, 60% as metabolites in urine; steady state at 7–8 days | No renal dose adjustment needed; allow 7–14 days between titration steps; slow offset after discontinuation (7–10 days to baseline) |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Peripheral edema | 10.8% (at 10 mg; 3.0% at 5 mg; 1.8% at 2.5 mg) | Dose-dependent; more common in women (14.6%) than men (5.6%); due to precapillary arteriolar vasodilation, not fluid retention — diuretics are typically ineffective; consider dose reduction or ACE-I/ARB combination to mitigate |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Fatigue | 4.5% (vs 2.8% placebo) | Not clearly dose-related; usually transient during first weeks of therapy |
| Dizziness | 3.4% (at 5–10 mg; 1.1% at 2.5 mg) | Dose-dependent; postural component possible especially in elderly or volume-depleted patients |
| Palpitation | 4.5% (at 10 mg; 1.4% at 5 mg) | Dose-related; reflex sympathetic response to vasodilation; typically benign but warrants cardiac assessment if persistent |
| Nausea | 2.9% (vs 1.9% placebo) | Not dose-related; usually self-limiting; consider taking with food |
| Flushing | 2.6% (at 10 mg; 1.4% at 5 mg) | Dose-related; more common in women (4.5%) than men (1.5%); related to peripheral vasodilation |
| Abdominal pain | 1.6% (vs 0.3% placebo) | Not dose-related; evaluate for other causes if persistent |
| Somnolence | 1.4% (vs 0.6% placebo) | Usually mild; advise caution with driving until individual response is known |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Worsening angina or acute MI | Rare | At initiation or dose increase | Particularly in severe obstructive CAD; hold or reduce dose; urgent cardiology evaluation |
| Severe hypotension | Rare | Usually with first dose or overdose | Gradual onset makes acute hypotension unlikely; supportive care with IV fluids and vasopressors if needed; risk higher with severe aortic stenosis |
| Hepatotoxicity (cholestasis/hepatitis) | Very rare | Weeks to months | Check LFTs if jaundice, dark urine, or unexplained malaise develops; discontinue if confirmed; postmarketing reports, some requiring hospitalization |
| Angioedema / hypersensitivity | Very rare | Any time during therapy | Discontinue immediately; emergency management as indicated; includes reports of erythema multiforme and Stevens-Johnson syndrome |
| Gingival hyperplasia | <1% | Months of use | Maintain rigorous oral hygiene; consider switching to a non-CCB agent if severe; typically reversible upon discontinuation |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Peripheral edema | Most common cause | Dose-related; primarily at 10 mg; more frequent in women; not responsive to diuretics |
| Dizziness / flushing | Less common | Usually transient; may resolve with dose reduction; consider timing of dose (bedtime) to minimize daytime symptoms |
Amlodipine-induced edema results from preferential arteriolar dilation that increases capillary hydrostatic pressure — it is not a sign of fluid overload. Diuretics are generally ineffective because the mechanism is not sodium retention. The most evidence-supported strategy is to add an ACE inhibitor or ARB, which dilates the venous side and rebalances capillary hemodynamics, reducing edema by 40–60% in clinical practice. Alternatively, reducing the amlodipine dose to 5 mg or lower significantly decreases edema incidence. Leg elevation and compression stockings offer symptomatic relief.
Drug Interactions
Amlodipine is primarily metabolised by CYP3A4, though it is considered a low-clearance drug with high bioavailability, which makes the magnitude of CYP3A4-mediated interactions generally moderate rather than dramatic. Amlodipine is itself a weak CYP3A4 inhibitor, which is clinically relevant for simvastatin and cyclosporine.
Amlodipine does not significantly interact with digoxin, warfarin, atorvastatin, ethanol, cimetidine, magnesium/aluminium antacids, or grapefruit juice at standard clinical doses. Amlodipine has been safely co-administered with thiazide diuretics, beta-blockers, ACE inhibitors, long-acting nitrates, NSAIDs, and oral hypoglycaemic agents in clinical trials (FDA PI).
Monitoring
-
Blood Pressure
Baseline, then every 2–4 weeks during titration; every 3–6 months once stable
Routine Measure in both supine and standing positions initially, especially in elderly. Full antihypertensive effect may not be apparent for 7–14 days after a dose change. Target BP per current guidelines (typically <130/80 mmHg for most adults). -
Heart Rate
Baseline, then at each BP check
Routine Amlodipine does not typically cause significant heart rate changes with chronic dosing. Reflex tachycardia is uncommon but should be assessed if patient reports palpitations. -
Peripheral Edema
At each visit
Routine Assess ankles and lower extremities for dose-dependent peripheral edema, especially in women and at 10 mg dose. Distinguish from signs of heart failure (elevated JVP, pulmonary crackles). Not responsive to diuretics. -
Hepatic Function
As clinically indicated
Trigger-based Check LFTs if patient develops jaundice, dark urine, unexplained fatigue, or right upper quadrant pain. Postmarketing reports of cholestatic hepatitis, some requiring hospitalization. Titrate slowly in patients with pre-existing hepatic impairment. -
Angina Symptoms
At initiation and dose changes
Trigger-based Monitor for worsening angina or new chest pain when starting or increasing the dose, particularly in patients with severe obstructive coronary artery disease. Acute MI has been reported rarely in this setting. -
Dental Health
Every 6–12 months
Routine Gingival hyperplasia is an uncommon but recognised class effect. Encourage good oral hygiene and regular dental check-ups. Reversible upon discontinuation if it occurs. -
Cyclosporine / Tacrolimus Levels
When initiating, adjusting, or stopping amlodipine
Trigger-based In transplant patients, amlodipine increases cyclosporine trough levels by ~40% on average. Monitor levels and renal function closely. Similar monitoring advisable for tacrolimus co-administration.
Contraindications & Cautions
Absolute Contraindications
- Known hypersensitivity to amlodipine or any component of the formulation. Hypersensitivity reactions including anaphylaxis, angioedema, erythema multiforme, and Stevens-Johnson syndrome have been reported.
Relative Contraindications (Specialist Input Recommended)
- Severe aortic stenosis: Symptomatic hypotension is possible; haemodynamically significant aortic stenosis reduces the patient’s ability to compensate for the reduction in peripheral resistance. Cardiology involvement is advised before initiating.
- Severe hepatic impairment: Half-life extends to approximately 56 hours with AUC increases of 40–60%. Start at 2.5 mg and titrate very slowly with specialist input. Hepatic metabolism is the dominant elimination pathway.
- Decompensated heart failure: Although amlodipine was not harmful in the PRAISE trial (NYHA III/IV on standard HF therapy), dihydropyridine CCBs are generally not recommended as primary agents in decompensated HF.
Use with Caution
- Severe obstructive coronary artery disease: Initiation or dose escalation may rarely precipitate worsening angina or acute myocardial infarction.
- Elderly patients: Decreased clearance results in higher plasma concentrations (AUC increase ~40–60%). Start at 2.5 mg once daily.
- Pregnancy: Limited human data; animal studies showed effects at supratherapeutic doses. Use only if the potential benefit justifies the risk to the fetus. Nifedipine or labetalol may be preferred where more safety data exist.
- Breastfeeding: Amlodipine is excreted in breast milk in small amounts (RID ~4.2%); infant plasma levels have been undetectable. The FDA PI recommends discontinuing nursing, but LactMed and recent data suggest it is likely compatible with breastfeeding.
- Concurrent strong CYP3A4 inhibitors: Monitor closely for hypotension and edema; dose reduction may be necessary.
Worsening angina and acute myocardial infarction can develop after starting or increasing the dose of amlodipine, particularly in patients with severe obstructive coronary artery disease. This is a class-level precaution for calcium channel blockers in severe CAD and is included in the Warnings and Precautions section of the prescribing information. While there is no formal boxed warning for amlodipine, clinicians should exercise heightened vigilance during initiation and dose titration in patients with known severe multivessel CAD.
Patient Counselling
Purpose of Therapy
Amlodipine is used to lower blood pressure and, in some patients, to treat or prevent chest pain (angina) by relaxing blood vessels. Lowering blood pressure helps reduce the risk of heart attack and stroke. The medicine works gradually, and you may not feel different — but it is still working. It is important to continue taking it every day even if you feel well, as high blood pressure usually causes no symptoms.
How to Take
Take amlodipine once daily at the same time each day, with or without food. If you miss a dose, take it as soon as you remember unless it has been more than 12 hours — in that case, skip the missed dose and take the next one at the regular time. Never take two doses at once. Do not stop taking amlodipine suddenly without consulting your prescriber, though there is no rebound effect.
Sources
- Pfizer Inc. NORVASC (amlodipine besylate) Tablets — Full Prescribing Information. Revised January 2013. FDA Label Primary regulatory source for all approved indications, dosing, adverse effects, interactions, and pharmacokinetic data in this monograph.
- Azor (amlodipine and olmesartan medoxomil) — Prescribing Information. Daiichi Sankyo, Inc. 2017. FDA Label Provides additional data on amlodipine clearance in elderly patients and combination therapy dosing strategies.
- Nissen SE, Tuzcu EM, Libby P, et al. Effect of antihypertensive agents on cardiovascular events in patients with coronary disease and normal blood pressure: the CAMELOT study: a randomized controlled trial. JAMA. 2004;292(18):2217–2225. doi:10.1001/jama.292.18.2217 Demonstrated 31% reduction in composite cardiovascular endpoints with amlodipine vs placebo in CAD patients; basis for the coronary artery disease indication.
- ALLHAT Officers and Coordinators. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the ALLHAT trial. JAMA. 2002;288(23):2981–2997. doi:10.1001/jama.288.23.2981 Landmark trial establishing amlodipine as equivalent to chlorthalidone for primary cardiovascular outcomes in high-risk hypertensive patients.
- Dahlof B, Sever PS, Poulter NR, et al. Prevention of cardiovascular events with an antihypertensive regimen of amlodipine adding perindopril as required versus atenolol adding bendroflumethiazide as required, in the ASCOT-BPLA trial. Lancet. 2005;366(9489):895–906. doi:10.1016/S0140-6736(05)67185-1 Showed superior cardiovascular outcomes with amlodipine-based regimen versus atenolol-based regimen; particularly relevant for stroke risk reduction.
- Packer M, O’Connor CM, Ghali JK, et al. Effect of amlodipine on morbidity and mortality in severe chronic heart failure (PRAISE). N Engl J Med. 1996;335(15):1107–1114. doi:10.1056/NEJM199610103351504 Demonstrated safety of amlodipine in NYHA III/IV heart failure; no worsening of HF outcomes, supporting its use in patients with concurrent HF.
- Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. J Am Coll Cardiol. 2018;71(19):e127–e248. doi:10.1016/j.jacc.2017.11.006 Current US hypertension guideline listing CCBs (including amlodipine) as a first-line class for initial antihypertensive therapy.
- Knuuti J, Wijns W, Saraste A, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J. 2020;41(3):407–477. doi:10.1093/eurheartj/ehz425 Recommends dihydropyridine CCBs as first-line antianginal agents alongside beta-blockers for chronic stable angina.
- Nayler WG. Amlodipine: the new generation calcium antagonist. Am J Cardiol. 1989;64(17):65I–70I. doi:10.1016/0002-9149(89)90968-0 Foundational paper describing amlodipine’s unique binding kinetics to the dihydropyridine receptor and its gradual onset/offset of action.
- Bulsara KG, Patel P, Cassagnol M. Amlodipine. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. NCBI Bookshelf Comprehensive review of amlodipine pharmacology, off-label uses, and clinical considerations; updated April 2024.
- Murdoch D, Heel RC. Amlodipine: a review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in cardiovascular disease. Drugs. 1991;41(3):478–505. doi:10.2165/00003495-199141030-00009 Definitive early PK review establishing volume of distribution (21 L/kg), protein binding, and elimination half-life ranges used in clinical practice.
- Meredith PA, Elliott HL. Clinical pharmacokinetics of amlodipine. Clin Pharmacokinet. 1992;22(1):22–31. doi:10.2165/00003088-199222010-00003 Detailed PK analysis confirming bioavailability of 60–65%, Tmax of 6–8 h, and the influence of hepatic and renal impairment on amlodipine disposition.
- Naito T, Kubono N, Deguchi S, et al. Amlodipine passage into breast milk in lactating women with pregnancy-induced hypertension and its estimation of infant risk for breastfeeding. J Hum Lact. 2015;31(2):301–306. doi:10.1177/0890334414559292 Key lactation study showing median relative infant dose of 4.2%, supporting likely compatibility of amlodipine with breastfeeding.
- Abernethy DR, Gutkowska J, Lambert MD. Amlodipine in elderly hypertensive patients: pharmacokinetics and pharmacodynamics. J Cardiovasc Pharmacol. 1988;12 Suppl 7:S67–S71. doi:10.1097/00005344-198812007-00014 Establishes the 40–60% AUC increase in elderly patients that supports the recommendation for lower starting doses in this population.