Pharm
Verapamil
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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
Tachycardia
s
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
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