What is the recommended dose of Verapamil (calcium channel blocker) for various conditions?

Verapamil Dosing Recommendations

For acute supraventricular tachycardia (SVT), give verapamil 2.5-5 mg IV over 2 minutes, repeating with 5-10 mg every 15-30 minutes as needed up to a maximum total dose of 20-30 mg. 1, 2, 3

Acute Management by Indication

Supraventricular Tachycardia (SVT/PSVT)

• Initial dose: 2.5-5 mg IV bolus over 2 minutes (administer over 3 minutes in elderly patients) 1, 2, 4
• Repeat dosing: If no response, give 5-10 mg IV every 15-30 minutes 1, 2, 3
• Maximum total dose: 20-30 mg 1, 2, 3
• Alternative regimen: An additional 10 mg (0.075-0.15 mg/kg) may be given 30 minutes after the first dose if no response 2
• Verapamil is a third-line agent after vagal maneuvers and adenosine fail or are contraindicated 2, 4

Atrial Fibrillation Rate Control

• Initial dose: 2.5-5 mg IV bolus over 2 minutes 1, 3
• Repeat dosing: 5-10 mg every 15-30 minutes if needed 1, 3
• Maximum total dose: 20-30 mg 1, 3
• Alternative regimen: 0.075-0.15 mg/kg IV bolus over 2 minutes, may give additional 10 mg after 30 minutes if no response, then 0.005 mg/kg/min infusion 1
• Use only in patients with narrow-complex tachycardias 1, 3

Chronic Oral Management

Supraventricular Tachycardia

• Initial dose: 120 mg daily 2, 4
• Titration: Increase as needed up to maximum 480 mg daily in divided doses or as single dose with extended-release formulations 2, 4
• Effectiveness demonstrated in trials at doses up to 480 mg/day 2

Atrial Fibrillation Rate Control

• Standard formulation: 40-120 mg three times daily 3
• Extended-release: 120-480 mg once daily 1, 3
• Typical maintenance range: 180-480 mg daily (extended-release) 1

Hypertension

• Initial dose: 180 mg extended-release once daily in the morning with food 5
• Lower initial dose: 120 mg daily may be warranted in elderly or small patients 5
• Titration: Upward titration based on response evaluated weekly, approximately 24 hours after previous dose 5
• Dose escalation: 240 mg each morning → 180 mg morning plus 180 mg evening → 240 mg morning plus 120 mg evening → 240 mg every 12 hours 5
• Antihypertensive effects evident within first week 5

Cluster Headache (Off-Label)

• Starting dose: 40 mg morning, 80 mg early afternoon, 80 mg before bed 6
• Titration: Add 40 mg on alternate days based on attack timing 6
• Effective range: Most patients require 200-480 mg daily, though some need 520-960 mg 6
• High-dose caution: Doses above 480 mg are off-label; 360 mg daily is the only dose proven effective in double-blind placebo-controlled trial 7
• Strict cardiac monitoring required with high doses due to risk of bradycardia, AV block, and syncope 7

Critical Contraindications

Absolute contraindications include: 1, 2, 4, 3

• AV block greater than first degree (without pacemaker)
• SA node dysfunction (without pacemaker)
• Decompensated heart failure or severe LV dysfunction (LVEF <40%)
• Hypotension or cardiogenic shock
• Wolff-Parkinson-White syndrome with atrial fibrillation or flutter
• Wide-complex tachycardias (unless known with certainty to be supraventricular)

Avoid concurrent use with beta-blockers due to risk of profound bradycardia and hypotension 2, 4, 3

Adverse Effects and Monitoring

Common Side Effects

• Hypotension: Most common adverse effect; have resuscitation equipment available 2, 4, 3
• Bradycardia: Monitor heart rate, especially with high doses 1, 3, 7
• AV block: ECG monitoring advised, particularly with doses >480 mg daily 3, 7
• Heart failure precipitation: Monitor in predisposed patients 1, 4

High-Dose Monitoring (>480 mg/day)

• Baseline and serial ECGs to detect bradycardia, AV block, or sick sinus syndrome 7
• French pharmacovigilance data documented syncope, complete AV block, and sinus bradycardia with doses 240-1200 mg daily 7
• Consider lower initial doses in elderly, hepatic impairment, and renal impairment 3

Clinical Pearls

• Verapamil works by slowing AV node conduction and increasing AV node refractoriness 2
• Negative inotropic effects make it unsuitable for patients with heart failure 3
• When switching from immediate-release to extended-release formulations, total daily dose in milligrams may remain the same 5
• For nocturnal cluster headache attacks, give higher evening doses; for morning attacks, set alarm 2 hours before waking to take medication 6
• In critically ill patients with severely impaired LV function, IV amiodarone may be preferred over verapamil for rate control 3