What is the efficacy and safety of verapamil (calcium channel blocker) 120 mg SR in patients with hypertension, angina, or arrhythmias, compared to alternative treatments?

Verapamil 120 mg SR: Efficacy and Safety Compared to Alternatives

Verapamil 120 mg SR is an effective second-line antihypertensive agent and appropriate for angina or supraventricular arrhythmias, but beta-blockers should be preferred as first-line therapy for most cardiovascular conditions, particularly in patients with prior MI, heart failure, or obstructive cardiomyopathy. 1

Primary Clinical Indications for Verapamil 120 mg SR

Hypertension

• Verapamil is recommended when beta-blockers are contraindicated or produce intolerable side effects, particularly in patients with concurrent angina or supraventricular tachycardia 2
• Start with 120 mg daily in the morning (lower initial dose for elderly or small patients), then titrate upward based on response evaluated weekly: 180 mg daily, then 240 mg daily, then divided dosing up to maximum 480 mg/day 2, 3
• Verapamil demonstrates greater efficacy in patients with higher pretreatment blood pressure, elderly patients, and those with low plasma renin activity 4
• The drug is particularly useful in elderly and Black populations who tend to have low-renin hypertension 5

Angina Pectoris

• Verapamil is effective for stable angina but should only be used when beta-blockers are contraindicated, unsuccessful, or cause unacceptable side effects 1
• The drug reduces angina frequency and prolongs treadmill capacity primarily through reduction in resting and submaximal exercise heart rate 5
• Verapamil has proven efficacy in reducing mortality and reinfarction rates after acute MI in patients without heart failure, with results similar to beta-blockers 6

Supraventricular Arrhythmias

• Verapamil is highly effective for terminating paroxysmal supraventricular tachycardia (PSVT) and controlling ventricular response in atrial fibrillation/flutter 1, 7
• For acute PSVT, give 2.5-5 mg IV bolus over 2 minutes (3 minutes in elderly), with repeat doses of 5-10 mg every 15-30 minutes to maximum 20-30 mg 1
• Oral verapamil provides prophylactic value in preventing PSVT recurrences and controlling ventricular rate during long-term therapy 7

Critical Contraindications and Precautions

Absolute Contraindications

• Severe left ventricular dysfunction (ejection fraction <30%) or moderate to severe heart failure symptoms 3
• Second- or third-degree AV block without functioning pacemaker 1, 2
• Sick sinus syndrome without pacemaker 2
• Wolff-Parkinson-White syndrome with atrial fibrillation/flutter 1, 3
• Hypotension (systolic BP <90 mmHg) 3

Critical Precautions

• Avoid verapamil in patients with modest to severe heart failure or bradyarrhythmias 1
• Exercise extreme caution when combining with beta-blockers due to increased risk of profound bradycardia, AV block, and heart failure 1, 2
• In hypertrophic cardiomyopathy, use with caution in patients with high gradients, advanced heart failure, or sinus bradycardia 1
• Verapamil should not be used in acute STEMI setting and is disappointing in early-MI management 1

Comparison to Alternative Treatments

Beta-Blockers (Preferred First-Line)

• Beta-blockers are superior to verapamil for patients with prior MI, heart failure with reduced ejection fraction, or obstructive hypertrophic cardiomyopathy 1
• Beta-blockers are the drugs of first choice for angina with coronary artery disease 1
• Verapamil may substitute for beta-blockers in hypertensive patients with chronic stable angina only if left ventricular dysfunction is absent 1

Diltiazem (Similar Alternative)

• Diltiazem has similar efficacy and contraindication profile to verapamil 1
• Both nondihydropyridine calcium channel blockers should be avoided in patients with modest to severe heart failure or bradyarrhythmias 1
• Diltiazem dosing: 15-20 mg IV over 2 minutes for acute arrhythmias, or 120-360 mg daily orally for chronic conditions 1

Dihydropyridine Calcium Channel Blockers

• Long-acting dihydropyridines (e.g., amlodipine) are preferred after acute MI for continuing ischemia when beta-blockers fail or are contraindicated 1
• Rapid-release nifedipine showed increased mortality in acute MI and should never be used 1
• Dihydropyridines are contraindicated in obstructive HCM due to potential harm 1

ACE Inhibitors/ARBs

• ACE inhibitors or ARBs should be administered early in STEMI with hypertension, particularly with anterior MI, LV dysfunction, heart failure, or diabetes 1
• These agents are potentially harmful in HCM patients with resting or provocable LVOT obstruction 1

Dosing Algorithm for Verapamil SR

Initial Dosing

1. Start with 120 mg once daily in the morning with food 3
2. Use 120 mg initial dose for elderly or small patients who may have increased response 3

Titration Schedule

1. Evaluate therapeutic efficacy and safety weekly, approximately 24 hours after previous dose 3
2. If inadequate response at 180 mg: advance to 240 mg each morning 3
3. If still inadequate: 180 mg morning plus 180 mg evening, or 240 mg morning plus 120 mg evening 3
4. Maximum: 240 mg every 12 hours 3

Monitoring Requirements

• Monitor blood pressure and heart rate regularly during titration 2
• Periodic liver function testing is prudent due to risk of hepatocellular injury 3
• Watch for symptomatic hypotension (occurs in 2.5% of patients), dizziness, or bradycardia 3

Common Pitfalls to Avoid

• Never combine verapamil with beta-blockers without extreme caution and close monitoring due to risk of profound bradycardia and heart failure 1, 2
• Do not use verapamil for wide-complex tachycardias unless the arrhythmia is known with certainty to be supraventricular 1
• Avoid in pre-excited atrial fibrillation/flutter as AV nodal blockade may accelerate ventricular response 1
• Do not use verapamil as first-line therapy in acute STEMI—it is not recommended and has been disappointing in this setting 1
• Reduce warfarin dose by 50% and digoxin dose by 30-50% when initiating verapamil due to drug interactions 3