What is verapamil used for and how is it dosed?

Verapamil: Uses and Dosing Guidelines

Verapamil is primarily used for supraventricular tachyarrhythmias, hypertension, and angina, with an initial oral dose of 120 mg daily (divided or as extended-release) up to 480 mg daily maximum, and for IV administration, 5-10 mg over at least 2 minutes for acute treatment of SVT. 1, 2

Primary Indications

Supraventricular Tachyarrhythmias

• First-line use: Treatment of paroxysmal supraventricular tachycardia (PSVT) 1
• Second-line use: Rate control in atrial fibrillation/flutter (when beta-blockers are contraindicated) 1
• Specialized use: Verapamil-sensitive idiopathic left ventricular tachycardia and right ventricular outflow tract tachycardia 1

Hypertension

• Effective first-line treatment for mild to moderate essential hypertension 3
• Particularly useful in elderly patients and those with asthma or COPD (where beta-blockers are contraindicated) 4

Angina

• Treatment of vasospastic (Prinzmetal's) angina 5
• Management of chronic stable angina 5

Dosing Guidelines

Oral Administration

• Initial dose: 120 mg daily in divided doses or as single dose with extended-release formulations 1
• Maximum daily dose: 480 mg daily in divided doses or as single dose with extended-release formulations 1
• Dosing frequency:
  • Immediate release: Usually divided into 3 times daily dosing
  • Extended-release: Once daily dosing 4

Intravenous Administration

• Initial dose: 5-10 mg (0.075-0.15 mg/kg) administered over at least 2 minutes 2
• Repeat dose: 10 mg 30 minutes after first dose if inadequate response 2
• Maximum total dose: 20-30 mg 6
• Alternative dosing scheme: 2.5-5 mg over 2 minutes, followed by repeated doses of 5-10 mg every 15-30 minutes up to a total dose of 20 mg 1, 6
• Administration requirements: Must be given under continuous ECG and blood pressure monitoring 2

Special Populations

• Elderly patients: Administer IV dose over at least 3 minutes; may require lower oral doses 2
• Hepatic/renal impairment: Use with caution; dose reduction may be necessary 1
• Pediatric dosing (IV):
  • 0-1 year: 0.1-0.2 mg/kg (usual range: 0.75-2 mg)
  • 1-15 years: 0.1-0.3 mg/kg (usual range: 2-5 mg, not to exceed 5 mg) 2

Contraindications and Precautions

Absolute Contraindications

• AV block greater than first degree or SA node dysfunction (without pacemaker) 1
• Decompensated systolic heart failure/severe LV dysfunction 1
• Cardiogenic shock 1
• Wolff-Parkinson-White syndrome with atrial fibrillation/flutter 1
• Concurrent use with dofetilide 1

Use with Caution

• Hypotension 1
• Hepatic or renal dysfunction 1, 7
• Concurrent use with other negative inotropic or chronotropic agents 7
• Multiple drug interactions due to CYP3A4 inhibition and P-glycoprotein effects 1

Monitoring Parameters

• Blood pressure and heart rate 2
• ECG monitoring (especially during IV administration) 2
• Signs of heart failure or pulmonary edema 1
• Liver function tests 1

Common Side Effects

• Hypotension 1
• Bradycardia 1
• Constipation 5
• Dizziness 5
• Headache 1
• Peripheral edema 1

Clinical Pearls

• Verapamil has a higher risk of negative inotropic effects compared to dihydropyridine calcium channel blockers 1
• For acute PSVT, adenosine is typically first-line due to shorter half-life, with verapamil as an alternative 1
• Avoid combining verapamil with beta-blockers due to risk of profound bradycardia or heart block 1, 7
• Verapamil has extensive first-pass metabolism resulting in only 20% oral bioavailability 7
• The drug has a biphasic elimination with terminal half-life of 2-5 hours after IV administration 2