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Verapamil
Aka: Verapamil, Calan, Phenylalkamine
- See Also
- Calcium Channel Blocker
- Calcium Channel Blocker Overdose
- Dihydropyridine Calcium Channel Blocker (e.g. Amlodipine, Nifedipine)
- Diltiazem
- Mibefradil
- Class
- Non-Dihydropyridine Calcium Channel Blocker
- Mechanism
- AV Node effects
- Slow AV Node Conduction
- Prolong AV Node refractory period
- Reduces myocardial Oxygen Consumption
- Negative chronotropic effect
- Negative inotropic effect
- Reduces Systemic Vascular Resistance
- Results from vasodilatation of vascular Smooth Muscle
- Counters negative inotropic effect
- More negative hemodynamic effects than Diltiazem
- Coronary vasodilatation
- 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
- Verapamil ineffective against Ventricular Tachycardia
- Sinus Node or AV Node dysfunction without Pacemaker
- AV Block
- Sick Sinus Syndrome
- Severe Congestive Heart Failure
- Concurrent Intravenous Beta Blocker use
- Indications
- Paroxysmal Supraventricular Tachycardia (90% effective)
- Terminates sustained reentry within AV Node
- Terminates AV Node limb of reentrant circuit
- Supraventricular Tachycardia
- Terminates AV Node reentry Tachycardias
- Slows ventricular response to Atrial Fibrillation
- Verapamil is highly effective
- Used for acute treatment and prevention
- Hypertension
-
Drug Interaction
- Increases Digitalis (Digoxin) level
-
Beta Blocker (see contraindications above)
- Pharmacokinetics
- Peak effect seen within 3-5 minutes of bolus injection
- Dosing
- Supraventricular Tachycardia
- Adults
- Initial Dose: 2.5 to 5.0 mg IV bolus over 3 min
- Subsequent: 5 mg IV every 15 min (Max 30 mg total)
- Children (8-15 years old)
- Initial: 0.1 mg/kg up to 2.5 mg IV over 1-2 min
- Subsequent: 0.2 mg/kg up to 5 mg after 15 min
- Hypertension
- Regular: 80 mg PO tid (MAX 360 mg/day)
- Extended: 240 mg PO qd (MAX 480 mg/day)
- Precautions: Transient Hypotension
- Results from peripheral vasodilation
- Countered by Intravenous Calcium Injection
- Consider prophylactic pretreatment with Calcium
- Marginal Blood Pressure
- Left Ventricular Dysfunction
- Adverse Effects
- See Calcium Channel Blocker