amlodipine
Summary
Amlodipine is a long-acting dihydropyridine calcium channel blocker used primarily for hypertension and angina. It selectively blocks L-type calcium channels in vascular smooth muscle, causing vasodilation and reduced blood pressure with minimal cardiac effects.
Detail
Amlodipine belongs to the dihydropyridine class of calcium channel blockers, which selectively inhibit L-type voltage-gated calcium channels in vascular smooth muscle cells. This blockade prevents calcium influx, leading to smooth muscle relaxation, vasodilation, and decreased peripheral vascular resistance. Unlike non-dihydropyridine calcium channel blockers (verapamil, diltiazem), amlodipine has minimal effects on cardiac conduction or contractility due to its vascular selectivity. It has an exceptionally long half-life (30-50 hours), allowing once-daily dosing. The drug undergoes hepatic metabolism via CYP3A4. Common side effects include peripheral edema (dose-dependent, due to preferential arteriolar vs. venular dilation), flushing, and dizziness. It's particularly effective in elderly patients and those with isolated systolic hypertension. Amlodipine can be used safely in patients with heart failure (unlike negative inotropic agents) and has neutral effects on glucose and lipid metabolism, making it suitable for diabetic patients.
Sources
- Katzung & Trevor's Basic and Clinical Pharmacology
- Goodman & Gilman's The Pharmacological Basis of Therapeutics
- First Aid for the USMLE Step 1
- Harrison's Principles of Internal Medicine
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