Overview
Amlodipine is a long-acting dihydropyridine calcium channel blocker used primarily for hypertension and angina. It produces vasodilation by inhibiting calcium influx into vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure without significantly affecting heart rate. Its once-daily dosing provides 24-hour antihypertensive coverage.
Mechanism of Action
Amlodipine inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle cells. This inhibition causes peripheral arterial vasodilation, reducing peripheral vascular resistance and blood pressure. It has greater selectivity for vascular smooth muscle than cardiac muscle, resulting in minimal effects on cardiac contractility and conduction.
Indications
- Treatment of hypertension
- Management of chronic stable angina
- Vasospastic (Prinzmetal's or variant) angina
Common Doses
- 2.5 mg
- 5 mg
- 10 mg
Dosage
Initial dose is 5 mg once daily for most patients, with a maximum dose of 10 mg daily. Dose titration should occur over 7-14 days. Elderly patients or those with hepatic impairment may require lower starting doses (2.5 mg daily).
Contraindications
- Hypersensitivity to amlodipine or other dihydropyridines
- Severe hypotension
Side Effects
- Peripheral edema
- Headache
- Flushing
- Dizziness
- Fatigue
- Nausea
- Palpitations
- Hypotension
- Rarely: gingival hyperplasia
Interactions
- CYP3A4 inhibitors (e.g., ketoconazole, itraconazole) may increase amlodipine levels
- Sildenafil and other PDE5 inhibitors may potentiate hypotensive effects
- Simvastatin dose should be limited to 20 mg daily when co-administered
Counseling Points
- Take once daily at same time each day
- May take with or without food
- Do not stop abruptly; consult provider for discontinuation
- Report swelling of feet/ankles, dizziness, or rapid heartbeat
- Avoid grapefruit juice which may increase drug levels
- Rise slowly from sitting/lying position to prevent dizziness