What is Diltiazem used for?

Diltiazem Uses and Clinical Applications

Diltiazem is primarily indicated for the management of chronic stable angina, angina due to coronary artery spasm, hypertension, and supraventricular tachyarrhythmias. 1, 2

Primary Indications

Cardiovascular Conditions

• Chronic stable angina: First-line or alternative treatment when beta-blockers are contraindicated or not tolerated 1, 3
• Variant angina/coronary artery spasm: Particularly effective due to coronary vasodilatory properties 1, 2
• Hypertension: Effective for blood pressure control 2, 4
• Supraventricular tachyarrhythmias: Particularly useful for rate control in atrial fibrillation with rapid ventricular response 5, 6

Mechanism of Action

Diltiazem is a non-dihydropyridine calcium channel blocker that:

• Inhibits calcium influx through L-type calcium channels in vascular smooth muscle and myocardium 2
• Decreases myocardial oxygen demand by reducing:
  • Afterload (peripheral vasodilation)
  • Heart rate (negative chronotropic effect)
  • Myocardial contractility (negative inotropic effect) 2
• Increases myocardial oxygen supply through coronary artery dilation 3
• Slows sinoatrial and atrioventricular node conduction 2

Clinical Considerations and Precautions

Contraindications

• Decompensated heart failure or severe left ventricular dysfunction 7, 8
• Sick sinus syndrome or advanced AV block (without pacemaker) 7
• Hypotension (systolic BP <90 mmHg) 7

Drug Interactions

• Statins: Moderate increases in exposure when combined with lovastatin or simvastatin; prefer non-CYP3A4-metabolized statins 2
• Beta-blockers: Increased risk of bradycardia and heart block when used in combination 7
• Ivabradine: Should not be used together due to risk of severe bradycardia 2

Adverse Effects

• Bradycardia: Discontinue if heart rate <50 beats/minute 7
• Hypotension: More common with higher doses; consider low-dose regimens (≤0.2 mg/kg IV) for acute situations 6
• AV block: Monitor for conduction abnormalities, especially with concomitant beta-blocker use 5
• Peripheral edema: Common side effect with all calcium channel blockers 2
• Constipation: Particularly with verapamil, less common with diltiazem 2

Special Populations

• Elderly patients: Increased sensitivity to hypotensive effects; start with lower doses 7
• Heart failure: Use with caution; dihydropyridine CCBs (amlodipine, felodipine) are preferred if CCB therapy is necessary 2, 8

Dosing Considerations

• Oral dosing:

  • Immediate-release: 30 mg every 6 hours or 60 mg every 8 hours
  • Extended-release: 120-360 mg once daily
  • Typical maintenance dose: 120-360 mg daily (extended release) 7

• IV dosing (for rapid atrial fibrillation):

  • Traditional dose: 0.25 mg/kg IV bolus over 2 minutes
  • Low-dose approach (≤0.2 mg/kg) may be equally effective with lower risk of hypotension 6

Clinical Pearls

• When selecting between calcium channel blockers, diltiazem offers a balance between the pure vasodilatory effects of dihydropyridines and the stronger negative inotropic effects of verapamil 8
• For patients with both hypertension and angina, diltiazem can effectively address both conditions 4
• In patients with non-Q wave myocardial infarction, diltiazem has shown reduction in subsequent cardiac events 5
• Consider electrophysiology study and catheter ablation as definitive treatment for recurrent SVT rather than long-term diltiazem therapy 7

Diltiazem remains a valuable medication in the cardiovascular armamentarium, particularly when beta-blockers are contraindicated or poorly tolerated, though careful monitoring is required especially in patients with compromised left ventricular function.