What are the uses of Verapamil (calcium channel blocker)?

Verapamil Uses in Clinical Practice

Verapamil is primarily indicated for the treatment of hypertension, supraventricular tachyarrhythmias, and angina, with specific efficacy in rate control for atrial fibrillation/flutter and termination of paroxysmal supraventricular tachycardias. 1, 2

Cardiovascular Indications

Hypertension

• Verapamil is FDA-approved for the treatment of hypertension, working by decreasing systemic vascular resistance without causing orthostatic hypotension or reflex tachycardia 1
• It reduces blood pressure by dilating peripheral arterioles, thereby decreasing total systemic resistance (afterload) 1
• Sustained-release formulations allow for once-daily dosing while maintaining 24-hour blood pressure control 3

Supraventricular Tachyarrhythmias

• Verapamil is a first-line treatment for stable narrow-complex tachycardias when adenosine or vagal maneuvers fail, administered at 2.5-5 mg IV over 2 minutes 2
• For acute rate control in atrial fibrillation or flutter, the recommended dose is 5-10 mg IV every 15-30 minutes to a total dose of 20-30 mg 2, 4
• It terminates most cases of paroxysmal supraventricular tachycardia (PSVT) by blocking conduction through the AV node 4, 5
• For PSVT that recurs after adenosine or fails to respond to adenosine, verapamil is an effective alternative 4

Angina

• Verapamil is effective in treating vasospastic (Prinzmetal's) angina and unstable angina at rest due to its coronary vasodilatory properties 1
• It dilates coronary arteries and arterioles in both normal and ischemic regions 1
• Verapamil is particularly useful when beta-blockers are contraindicated, such as in patients with asthma or chronic obstructive pulmonary disease 3

Mechanism of Action

• Verapamil is a non-dihydropyridine calcium channel blocker that inhibits calcium influx through L-type calcium channels 6, 1
• It has significant effects on cardiac tissue, producing:
  • Negative inotropic effects (decreased myocardial contractility)
  • Negative chronotropic effects (decreased heart rate)
  • Negative dromotropic effects (slowed AV conduction) 6, 1
• These effects make it particularly useful for controlling ventricular rate in supraventricular arrhythmias 2, 4

Contraindications and Precautions

• Verapamil should not be used in patients with:

  • Significant left ventricular dysfunction or heart failure 2, 4
  • Cardiogenic shock 2
  • Second or third-degree AV block without a pacemaker 2
  • Sick sinus syndrome (may induce sinus arrest or sinoatrial block) 1
  • Concurrent beta-blocker therapy (risk of profound bradycardia and hypotension) 2
  • Wolff-Parkinson-White syndrome with atrial fibrillation (may accelerate ventricular rate) 4, 1

• Use with caution in:

  • Elderly patients (may have prolonged elimination half-life) 1
  • Patients with hepatic impairment (reduced first-pass metabolism) 1
  • Patients with severe obstructive hypertrophic cardiomyopathy 2

Common Side Effects

• Constipation (most common non-cardiovascular side effect) 2, 6
• Hypotension 2, 6
• Bradycardia 2, 6
• Peripheral edema 2, 6
• AV block 1

Clinical Pearls

• Calcium pretreatment (1g IV calcium gluconate) before verapamil administration can minimize hypotensive effects without reducing antiarrhythmic efficacy 7, 8
• Verapamil can be combined with other antihypertensive agents (diuretics, ACE inhibitors) for enhanced blood pressure control in resistant hypertension 3
• For rate control in atrial fibrillation, verapamil is often more effective than diltiazem but has more pronounced negative inotropic effects 4
• Verapamil should not be administered to patients with wide-complex tachycardias of unknown origin, as it may worsen hemodynamics in ventricular tachycardia 4
• When used for PSVT, monitor for recurrence and consider longer-acting AV nodal blocking agents for maintenance therapy 4