What are the uses and dosages of Verapamil?

Verapamil Uses and Dosages

Verapamil is primarily used for supraventricular tachyarrhythmias, hypertension, and angina pectoris, with specific dosing regimens for each indication based on administration route and patient factors. 1

Intravenous (IV) Administration

For Supraventricular Tachycardia (SVT):

• Initial dose: 2.5-5 mg IV bolus over 2 minutes (3 minutes in older patients)
• Repeat dose: 5-10 mg every 15-30 minutes if needed
• Maximum total dose: 20-30 mg
• Alternative regimen: 5 mg bolus every 15 minutes to a total dose of 30 mg 1, 2

Administration Requirements:

• Must be administered as slow IV injection under continuous ECG and blood pressure monitoring
• Solution must be clear and vial seal intact
• Unused solution should be discarded immediately 3

Pediatric Dosing:

• 0-1 year: 0.1-0.2 mg/kg (0.75-2 mg) over at least 2 minutes
• 1-15 years: 0.1-0.3 mg/kg (2-5 mg) over at least 2 minutes (not exceeding 5 mg)
• Repeat doses may be given after 30 minutes if needed 3

Oral Administration

For Hypertension:

• Initial dose: 120 mg daily in divided doses or as a single dose with long-acting formulations
• Maintenance dose: Up to 480 mg daily in divided doses or as a single dose with long-acting formulations 1

For Angina:

• Similar dosing to hypertension, typically starting at 120 mg daily and titrating based on response 4, 5

Contraindications and Precautions

Absolute Contraindications:

• AV block greater than first degree or SA node dysfunction (without pacemaker)
• Decompensated heart failure or severe left ventricular dysfunction
• Hypotension
• Wolff-Parkinson-White syndrome with atrial fibrillation/flutter 1, 2

Use with Caution:

• Impaired ventricular function
• Wide-complex tachycardias (unless confirmed supraventricular origin)
• Hepatic or renal dysfunction 1, 2

Drug Interactions:

• Verapamil is a moderate CYP3A4 inhibitor and P-glycoprotein inhibitor
• Contraindicated with dofetilide
• Significant interactions with multiple medications including digoxin, beta-blockers, and statins 1

Adverse Effects

Cardiovascular:

• Hypotension
• Bradycardia
• Worsening heart failure in patients with pre-existing ventricular dysfunction
• Pulmonary edema in patients with hypertrophic cardiomyopathy 1

Other:

• Abnormal liver function tests
• Headache
• Constipation
• Dizziness 1

Special Considerations

For Multifocal Atrial Tachycardia:

• Calcium pretreatment (1g IV calcium gluconate) may reduce hypotension without affecting antiarrhythmic efficacy 6

For Specific Ventricular Tachycardias:

• May be effective in certain forms of ventricular tachycardia, particularly verapamil-sensitive idiopathic left ventricular tachycardia and right ventricular outflow tract tachycardia 1, 7

Elderly Patients:

• Administer IV doses over at least 3 minutes to minimize adverse effects
• May have enhanced antihypertensive effect in older patients 3, 4

Monitoring

• Continuous ECG monitoring during IV administration
• Blood pressure monitoring during IV administration
• Watch for signs of hypotension, bradycardia, or worsening heart failure 2

Remember that combining verapamil with beta-blockers requires extreme caution due to potential additive negative inotropic and chronotropic effects 8.