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Verapamil hydrochloride: pharmacological properties and role in cardiovascular therapeutics
Insights
Verapamil hydrochloride is a calcium channel blocker used to treat heart rhythm disorders and angina. While effective, potential side effects like constipation and AV block require careful patient monitoring.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Verapamil hydrochloride is a prototype calcium antagonist.
- It is approved for supraventricular tachyarrhythmias and angina management.
Purpose of the Study:
- To review the established and potential therapeutic roles of verapamil.
- To outline its mechanism of action, hemodynamic effects, and side effect profile.
Main Methods:
- Review of controlled trials and clinical data on verapamil.
- Analysis of electrophysiologic and hemodynamic effects.
Main Results:
- Verapamil effectively treats supraventricular tachyarrhythmias and various forms of angina.
- It demonstrates efficacy in obstructive cardiomyopathies.
- Potential roles in hypertension and Raynaud's phenomenon require further investigation.
Conclusions:
- Verapamil is a valuable therapeutic agent for specific cardiovascular conditions.
- Its mechanism involves blocking calcium channels in the heart and smooth muscle.
- Common side effects include constipation and dizziness; serious adverse events like AV block can occur.
Abstract:
Verapamil hydrochloride, a prototype calcium antagonist, is now marketed in the United States for the acute treatment of supraventricular tachyarrhythmias and for chronic management of vasospastic and chronic stable angina. It inhibits the slow inward channel in in the heart and blocks calcium influx in smooth muscle. Its intrinsic negative inotropic action, which is apparent in isolated tissues, is offset in vivo by peripheral vasodilation. It has a mild, noncompetitive sympathetic antagonist effect; its most important electrophysiologic action is a depression of AV nodal conduction, accounting for its effect in supraventricular tachyarrhythmias. Its hemodynamic actions are characterized by a complex interplay of changes in preload, afterload, contractility, heart rate, and coronary blood flow. It does not depress cardiac function, except in severe heart failure. The drug has a mild dilator action on coronary arteries and reverses ergonovine-induced vasoconstriction. Controlled trials have established its role in Prinzmetal's variant angina, unstable angina, and chronic stable angina. It has also been found to be effective in obstructive cardiomyopathies. The potential role of verapamil in such conditions as hypertension, cardioprotection, and Raynaud's phenomenon needs further evaluation; at present these indications have not been approved by the Food and Drug Administration. The most common side effects include constipation, skin rash, and dizziness; AV block, heart failure, and sinus arrest may occasionally be encountered, especially when ventricular function is compromised or conduction system disease is present.