Are flecainide and diltiazem in the same class of medications?

Flecainide and Diltiazem Belong to Different Antiarrhythmic Drug Classes

No, flecainide and diltiazem are not in the same class of medications. Flecainide is a Class IC antiarrhythmic drug, while diltiazem is a non-dihydropyridine calcium channel blocker.

Classification and Mechanisms of Action

Flecainide

• Class: Class IC antiarrhythmic agent 1
• Mechanism: Blocks sodium channels, producing a dose-related decrease in intracardiac conduction in all parts of the heart with greatest effect on the His-Purkinje system 1
• Electrophysiologic effects: Decreases conduction velocity, particularly in the ventricles, with less pronounced effects on AV nodal conduction 1, 2
• Pharmacology: Local anesthetic activity with membrane stabilizing properties 3

Diltiazem

• Class: Non-dihydropyridine calcium channel blocker (benzothiazepine class) 4
• Mechanism: Blocks L-type calcium channels 4
• Electrophysiologic effects: Slows AV nodal conduction, prolongs AV nodal refractory period 5
• Pharmacology: Vasodilator with negative chronotropic and dromotropic effects 4

Clinical Applications

Flecainide

• Indicated for:
  • Suppression of ventricular ectopic beats 3
  • Treatment of ventricular tachycardia in patients without structural heart disease 6
  • Management of supraventricular tachycardias including atrial fibrillation 2
  • May be reasonable for junctional tachycardia in patients without structural heart disease 5

Diltiazem

• Indicated for:
  • Acute management of narrow-QRS tachycardias 5
  • Ongoing management of junctional tachycardia 5
  • Rate control in atrial fibrillation and flutter 5
  • Hypertension and angina (not covered in the provided evidence)

Important Contraindications and Precautions

Flecainide

• Contraindicated in:
  • Structural heart disease, particularly ischemic heart disease 7
  • Left bundle branch block 5
  • Severe fibrosis 5

Diltiazem

• Contraindicated in:
  • AV block greater than first degree or SA node dysfunction (without pacemaker) 5
  • Decompensated systolic heart failure/LV dysfunction 5
  • Cardiogenic shock 5
  • WPW with AF/atrial flutter 5

Drug Interactions

Flecainide

• Interacts with verapamil, digoxin, and other drugs with SA/AV nodal-blocking properties 5

Diltiazem

• Is a substrate of CYP3A4 and a moderate CYP3A4 inhibitor 5
• Interacts with numerous medications including apixaban, cyclosporine, everolimus, and flecainide 5

Clinical Implications of Different Classifications

Understanding that these medications belong to different classes is crucial for clinical decision-making:

1. They have different safety profiles in various patient populations
2. Their contraindications differ significantly
3. They may be used in combination for certain arrhythmias, leveraging their different mechanisms
4. Drug selection should be based on the specific arrhythmia mechanism and patient characteristics

The 2019 ESC guidelines have downgraded recommendations for both drugs in certain scenarios, but they remain important options in the management of various arrhythmias when used appropriately 5.