Amlodipine is a long-acting dihydropyridine calcium-channel blocker (CCB) widely used for hypertension and angina. It inhibits L-type calcium influx into vascular smooth muscle, causing peripheral arteriolar vasodilation with minimal effect on cardiac conduction. The result is reduced systemic vascular resistance (afterload) and improved coronary blood flow. Because it has a slow onset and a long elimination half-life (≈30–50 hours), amlodipine provides smooth 24-hour blood-pressure control with once-daily dosing and a relatively low risk of reflex tachycardia compared with short-acting CCBs.
Blood-pressure reduction with amlodipine is dose-dependent and comparable to ACE inhibitors, ARBs, and thiazides. In outcome trials, CCB-based regimens reduce stroke and major cardiovascular events when blood pressure is adequately controlled. In chronic stable or vasospastic (Prinzmetal) angina, amlodipine improves exercise tolerance and decreases angina frequency by reducing myocardial oxygen demand (via afterload reduction) and enhancing epicardial and microvascular coronary perfusion. Unlike non-dihydropyridine CCBs (verapamil/diltiazem), amlodipine has little effect on heart rate or AV conduction and is generally safe in combination with beta-blockers.
Amlodipine is absorbed orally with bioavailability ≈60–80%, reaches peak plasma concentrations in 6–12 hours, and achieves steady state after 7–8 days. It is extensively metabolised hepatically (CYP3A4) to inactive metabolites and excreted via urine and faeces. Elderly patients and those with hepatic impairment may have higher exposure and need slower titration. Because of its slow offset, missed doses are less likely to cause rebound hypertension than with some other antihypertensives.
Therapy should be individualised to overall cardiovascular risk. Best results occur when amlodipine is combined with lifestyle modification: weight control, sodium restriction, regular physical activity, moderation of alcohol, and smoking cessation. For many patients, fixed-dose combinations with an ARB or ACE inhibitor simplify regimens and improve adherence.
Blood pressure typically improves within the first week, with maximal effect after 1–2 weeks of a stable dose. A home BP diary helps clinicians fine-tune therapy.
Amlodipine is well tolerated by most people. Adverse effects arise mainly from vasodilation and fluid shift; they are dose-related and often improve with time or dose adjustment.
Peripheral oedema is the main reason for discontinuation. It is usually dose-related and reflects pre-capillary dilation rather than salt/water retention; adding an ACE inhibitor or ARB often mitigates oedema better than adding a diuretic.
Encourage patients to monitor blood pressure at home, keep a log, and report persistent swelling, new chest pain, or troublesome dizziness.
Amlodipine is metabolised by CYP3A4. Interactions are typically modest but clinically relevant in select combinations.
Always provide an up-to-date list of medicines and supplements to your clinician and pharmacist. Avoid starting or stopping interacting drugs without advice.
Missed dose: take it when remembered the same day; if nearly time for the next dose, skip the missed dose and resume the usual schedule. Do not double up.
Accidental double dose: may cause flushing, marked hypotension, or dizziness. Sit or lie down, hydrate, and contact a clinician or pharmacist if unwell or symptoms persist.
Large overdose (emergency): profound vasodilation can produce severe hypotension, reflex tachycardia, and (rarely) shock. Seek urgent medical attention.
Because amlodipine is highly protein bound, haemodialysis is unlikely to help.
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