Verapamil
Pharmacology
Verapamil is a calcium channel blocker medication that is primarily used to treat high blood pressure, angina, and certain types of arrhythmia. It works by relaxing the muscles of the heart and blood vessels, which improves blood flow and decreases blood pressure.
Verapamil is classified as a class IV antiarrhythmic agent and a phenylalkylamine calcium channel blocker. It inhibits the influx of extracellular calcium ions into myocardial and vascular smooth muscle cells, causing dilatation of the main coronary and systemic arteries and decreasing myocardial contractility.
Clinical Use
Verapamil is used in the treatment of various cardiovascular conditions. It is effective in treating angina pectoris, essential hypertension, and cardiac arrhythmias such as supraventricular tachycardia, atrial flutter, and atrial fibrillation. It is also used in the prevention of migraine headaches.
Mechanism of Action
Verapamil's therapeutic effects are achieved through its ability to block voltage-dependent L-type calcium channels in the heart and blood vessels. By blocking these channels, Verapamil reduces the influx of calcium ions into the cells, which leads to a decrease in contractility and conductivity in the heart, and vasodilation in the blood vessels.
Side Effects
Like all medications, Verapamil can cause side effects. Common side effects include headache, dizziness, constipation, and edema. More serious side effects can include slow heart rate, low blood pressure, and heart failure. It is important to monitor patients closely for these side effects, especially when initiating therapy or increasing dosage.
Interactions
Verapamil can interact with a number of other medications, which can alter its effectiveness or increase the risk of side effects. For example, it can interact with beta-blockers, increasing the risk of heart failure or producing additive effects on heart rate and blood pressure. It can also interact with digoxin, increasing its serum levels and potentially leading to digoxin toxicity.
Dosage and Administration
Verapamil is available in both immediate-release and extended-release forms. The dosage of Verapamil is individualized for each patient based on their specific condition and response to therapy. It is typically taken orally, with or without food.