II. Indications
-
Hypertension
- Consider Dihydropyridine Calcium Channel Blocker (e.g. Amlodipine) instead if Heart Rate control is not needed
-
Atrial Fibrillation with Rapid Ventricular Response
- Highly effective at controlling ventricular rate
- Paroxysmal Supraventricular Tachycardia
-
Supraventricular Tachycardia
- Terminates AV Node reentry Tachycardias
III. Contraindications
-
Wolff-Parkinson-White Syndrome with Atrial Fibrillation
- Paroxysmal accelerated ventricular response
- Risk of progression into Ventricular Fibrillation
-
Wide Complex Tachycardia (unless supraventricular)
- Risk of severe Hypotension
- May progress into Ventricular Fibrillation
- Sinus Node or AV Node dysfunction without Pacemaker
- Severe Congestive Heart Failure
- Concurrent Intravenous Beta Blocker use
IV. Mechanism
- See Calcium Channel Blocker
-
General
- Non-Dihydropyridines are active at cardiac and vascular Smooth Muscle
- Contrast with Dihydropyridines which are primarily active only at vascular Smooth Muscle
- Calcium Channel Blockers decrease Smooth MuscleCalcium influx resulting in vascular Smooth Muscle relaxation
- AV Node effects
- Less negative hemodynamic effects for Diltiazem than Verapamil
- Potent negative chronotropic effect
- Minimal negative inotropic effect
- Diltiazem effects Left Ventricular Dysfunction less
- Coronary vasodilatation
VI. Adverse Effects
- See Calcium Channel Blocker
- Constipation (esp. Verapamil)
VII. Drug Interactions
- CYP3A4 (e.g. Simvastatin, Colchicine)
VIII. References
- (2022) Presc Lett 29(11): 64-5