What is the classification of Amlodipine (calcium channel blocker)?

Amlodipine Classification

Amlodipine is a dihydropyridine calcium channel blocker that selectively inhibits L-type calcium channels in vascular smooth muscle, producing peripheral arterial vasodilation with minimal effects on cardiac conduction or contractility. 1, 2

Structural and Pharmacological Classification

• Chemical class: Amlodipine belongs to the dihydropyridine subclass of calcium channel blockers, distinguished from nondihydropyridines (diltiazem and verapamil) by its chemical structure and selectivity profile 1, 2

• Mechanism: It inhibits transmembrane calcium influx through voltage-gated L-type calcium channels, with preferential selectivity for vascular smooth muscle cells over cardiac myocytes 2

Key Distinguishing Features from Other Calcium Channel Blockers

Dihydropyridines vs. Nondihydropyridines

• Vascular selectivity: Dihydropyridines like amlodipine have high selectivity for L-type channels in the vasculature, producing decreased coronary and systemic vascular resistance with minimal direct cardiac effects 1

• Cardiac effects: Unlike nondihydropyridines (diltiazem, verapamil), amlodipine has minimal effects on cardiac conduction, atrioventricular node function, sinus node function, or myocardial contractility 3, 1

• Negative inotropic effects: While nondihydropyridines produce pronounced negative inotropic and chronotropic effects, amlodipine's negative inotropic effects are detectable only in vitro and not at therapeutic doses in intact animals 2

Clinical Implications of Classification

Heart Failure Considerations

• Dihydropyridines (including amlodipine): Not recommended as routine treatment for heart failure with reduced ejection fraction (HFrEF), though they showed neutral effects on mortality in trials and may be used for hypertension management when needed 1, 3

• Nondihydropyridines: Contraindicated in HFrEF due to myocardial depression and association with worsening heart failure outcomes 1

Pharmacokinetic Profile

• Long-acting characteristics: Amlodipine has a half-life of 35-50 hours, allowing once-daily dosing with sustained 24-hour blood pressure control and minimal fluctuation between doses 4, 5, 6

• Metabolism: All calcium channel blockers, including amlodipine, are metabolized by hepatic cytochrome P450 3A4 1

Drug Interaction Considerations

• With other calcium channel blockers: Nondihydropyridines (diltiazem, verapamil) should not be combined with ivabradine due to CYP3A4 interactions and risk of severe bradycardia 1

• In cancer patients: Nondihydropyridines are contraindicated with VEGF inhibitors as they induce CYP3A4, increasing drug levels; dihydropyridines like amlodipine are preferred alternatives 1

FDA-Approved Indications

• Hypertension: Treatment of elevated blood pressure through peripheral arterial vasodilation 2

• Chronic stable angina: Reduces myocardial oxygen demand by decreasing afterload and rate-pressure product 2

• Vasospastic (Prinzmetal's) angina: Blocks coronary artery constriction and restores blood flow 2