Diltiazem Dosage and Usage for Cardiovascular Conditions
For treating hypertension, angina, and heart rhythm disorders, diltiazem should be dosed at 30-90 mg orally 3-4 times daily (total daily dose 90-360 mg) for immediate release formulations, or 120-360 mg once daily for extended-release formulations, with careful monitoring for bradycardia and hypotension. 1
Dosing Guidelines by Condition
Hypertension
- Immediate-release: 30-90 mg 3-4 times daily (total daily dose: 90-360 mg)
- Extended-release: Start at 120-240 mg once daily, titrate up to 360 mg once daily
- Optimal dosage often exceeds 240 mg for adequate 24-hour control
- Median effective dose: 300 mg/day 1
Angina (Stable and due to Coronary Artery Spasm)
- Immediate-release: 30 mg 4 times daily (total daily dose: 120 mg) 1, 2
- Extended-release: Start at 120 mg once daily, titrate up to 240-360 mg once daily 1
- Diltiazem is FDA-approved for management of chronic stable angina and angina due to coronary artery spasm 2
Heart Rhythm Disorders (Atrial Fibrillation/Flutter, SVT)
- IV administration: Initial dose 0.25 mg/kg IV bolus over 2 minutes, followed by maintenance infusion at 5-15 mg/hour 1
- Effective for terminating supraventricular tachycardia and controlling ventricular response in atrial fibrillation/flutter 3
Important Contraindications and Precautions
Absolute Contraindications
- Left ventricular dysfunction (LVEF <40%)
- Decompensated heart failure
- AV block greater than first degree
- Sick sinus syndrome
- Cardiogenic shock
- Pre-excitation syndromes (e.g., Wolff-Parkinson-White syndrome) 1
Drug Interactions
- Avoid combination with beta-blockers when possible due to increased risk of bradycardia and heart block 1
- Use caution with digitalis as additive effects on cardiac conduction may occur 2
Monitoring Requirements
- Blood pressure response
- Heart rate and cardiac conduction
- Signs of fluid retention (edema)
- Symptoms of hypotension or bradycardia 1
- Continuous cardiac monitoring is necessary when initiating IV therapy to assess for bradycardia or conduction abnormalities 1
Common Side Effects
- Hypotension
- Dizziness
- Flushing
- Bradycardia
- Edema 1
Clinical Pearls
- Avoid fluid boluses to counteract diltiazem-induced hypotension, especially in patients with heart failure or LV dysfunction 1
- Diltiazem has a negative inotropic effect and should be used with caution in patients with impaired ventricular function 2
- Although diltiazem lowers myocardial oxygen demand through reduction in heart rate, blood pressure, and cardiac contractility, it should not be used in heart failure with reduced ejection fraction 1, 4
- Diltiazem appears to have a regulatory effect on heart rate: it reduces tachycardia without inducing excessive bradycardia in patients with normal baseline heart rates 5
- For rate control in atrial fibrillation with LV dysfunction, beta-blockers or digoxin are preferred over diltiazem 1
Alternative Therapies When Diltiazem is Contraindicated
- For hypertension with LV dysfunction: ACE inhibitors, ARBs, or dihydropyridine calcium channel blockers 1
- For angina with LV dysfunction: Nitrates and beta-blockers 1
- For rate control in atrial fibrillation with LV dysfunction: Beta-blockers or digoxin 1
Remember that diltiazem may rarely result in abnormally slow heart rates or second- or third-degree AV block, particularly in patients with sick sinus syndrome (0.48% of patients) 2. When using diltiazem for cardiovascular conditions, careful monitoring of cardiac parameters is essential for safe and effective therapy.