What is the typical dosage and treatment regimen for Verapamil (calcium channel blocker) in managing high blood pressure, angina, and heart rhythm disorders?

Verapamil Dosage and Treatment Regimens for Cardiovascular Conditions

For managing high blood pressure, angina, and heart rhythm disorders, verapamil is typically dosed at 40-120 mg three times daily for immediate-release formulations or 120-480 mg once daily for extended-release formulations, with specific dosing adjusted based on the condition being treated and patient response. 1

Dosing for Specific Conditions

Hypertension

• Initial oral dosing: 40-80 mg three times daily (immediate-release) or 120-240 mg once daily (extended-release) 1
• Maintenance dosing: 120-360 mg daily in divided doses or as extended-release formulation 1
• Maximum daily dose: 480 mg 1
• For mild to moderate hypertension, 120 mg twice daily may be as effective as 120 mg three times daily and may improve patient compliance 2

Angina

• Immediate-release: 80-120 mg three times daily 1
• Extended-release: 120-480 mg once daily 1
• Effective for both stable exertional angina and unstable angina at rest 3, 4
• Reduces anginal frequency and nitroglycerin consumption significantly compared to placebo 4

Supraventricular Tachyarrhythmias

• Acute IV administration: 2.5-10 mg IV bolus over 2 minutes (3 minutes in older patients) 1, 5
• Repeat dose: 10 mg after 30 minutes if initial response inadequate 5
• Oral maintenance: 40-120 mg three times daily or 120-480 mg once daily (extended-release) 1

Administration Guidelines

Intravenous Administration

• Must be administered as a slow IV injection over at least 2 minutes (3 minutes in elderly) 5
• Requires continuous ECG and blood pressure monitoring 5
• For PSVT: 2.5-5 mg IV bolus over 2 minutes; may repeat with 5-10 mg every 15-30 minutes to maximum total dose of 20 mg 1
• Alternative regimen: 5 mg bolus every 15 minutes to total dose of 30 mg 1

Oral Administration

• Can be taken with or without food
• Extended-release formulations should be swallowed whole, not crushed or chewed
• Dosing should be spaced evenly throughout the day for immediate-release formulations

Precautions and Contraindications

Absolute Contraindications

• Severe left ventricular dysfunction (LVEF <40%) 1
• Cardiogenic shock 1
• Heart failure with pulmonary congestion 1
• Sick sinus syndrome or AV block greater than first degree (without pacemaker) 1
• Atrial fibrillation/flutter with accessory pathway (WPW syndrome) 1

Use with Caution

• Concomitant use with beta-blockers (increased risk of bradycardia and heart block) 1
• Hepatic impairment (reduce dose) 1
• Elderly patients (administer more slowly, consider lower doses) 5
• Significant drug interactions with CYP3A4 substrates and inhibitors 1

Monitoring

• Blood pressure and heart rate should be monitored regularly
• ECG monitoring during initiation of therapy, particularly with IV administration
• Assess for signs of heart failure or hypotension
• Watch for common adverse effects: constipation, dizziness, headache, peripheral edema, and bradycardia 1

Clinical Pearls

• Verapamil should not be given to patients with wide-complex tachycardias unless known with certainty to be supraventricular in origin 1
• For hypertension, verapamil may be combined with diuretics if monotherapy is inadequate 2
• In angina, verapamil has the advantage of increasing rather than decreasing cardiac output compared to beta-blockers 6
• Calcium pretreatment (1g IV calcium gluconate) may reduce verapamil-induced hypotension without preventing its antiarrhythmic effect 7

Remember that verapamil is a non-dihydropyridine calcium channel blocker with significant effects on cardiac conduction, making it particularly useful for rate control in atrial arrhythmias but requiring caution in patients with conduction system disease or heart failure.