Amlodipine is a long-acting dihydropyridine calcium channel blocker primarily used to treat hypertension and angina. It works by selectively inhibiting L-type calcium channels, primarily in vascular smooth muscle cells, which reduces calcium influx. This leads to vasodilation of peripheral arteries, lowering peripheral vascular resistance and thereby decreasing blood pressure. Unlike some other calcium channel blockers, amlodipine has minimal direct effects on cardiac contractility or conduction at therapeutic doses.
While not typically recommended in heart failure, amlodipine may be used if other medications are not sufficient for treating high blood pressure or heart-related chest pain. It is taken by mouth and has an effect that lasts for at least a day.
Key pharmacologic effects for a clinical pharmacist:
- Causes arterial vasodilation, reducing afterload and myocardial oxygen demand.
- Helps relieve angina by improving coronary blood flow through arterial dilation and preventing coronary artery spasm.
- Has a gradual onset and long half-life (about 30-50 hours), enabling once-daily dosing.
- Does not significantly alter heart rate or myocardial contractility in vivo, making it generally well-tolerated in patients with cardiac conditions.
- It is metabolized by CYP3A4, so drug interactions are important to monitor.
- Dose adjustment may be needed in hepatic impairment and elderly patients. Safety in pregnancy is unclear.
Common side effects include peripheral edema, headache, dizziness, flushing, feeling tired, abdominal pain, and nausea.
Serious side effects may include hypotension or heart attack. Whether the use is safe during pregnancy or breastfeeding is unclear. When used by people with liver problems, and in elderly individuals, doses should be reduced. Amlodipine works partly by increasing the size of arteries.
For pharmacists, important considerations include monitoring blood pressure and edema, educating patients about adherence and side effect recognition, and reviewing potential interactions, especially with CYP3A4 inhibitors or inducers.
In summary, amlodipine effectively lowers blood pressure and treats angina via vascular smooth muscle relaxation with a favorable safety and dosing profile suitable for chronic management of cardiovascular conditions