Verapamil

Administration

• Type: Calcium channel blocker
• Dosage Forms:
• Routes of Administration: IV, PO
• Common Trade Names:

Adult Dosing

• Atrial fibrillation, paroxysmal SVT
  • IV: 5-10mg (0.075-0.15 mg/kg), may give an initial 10mg IV after 30 minutes if inadequate response
  • PO: 240-48 mg daily in 3-4 divided doses
• Angina, hypertension: 80-120mg PO 3 times per day

Pediatric Dosing

• Afib/flutter, SVT
  • IV 0.1-0.2 (<1yo) or 0.1-0.3 (>1yo) mg/kg. Repeat after 30 minutes if inadequate response
  • PO: 4-10 mg/kg/day in 3 divided doses

Special Populations

• Pregnancy Rating: Category C, verapapmil crosses the placenta and can cause adverse fetal effects such as heart block, hypotension, and bradycardia
• Lactation risk: Present in breast milk with relative infant dose of <1% which is considered safe for the infant.
• Renal dosing: Can accumulate causing increased effects, monitor closely and consider lowering dose.
• Hepatic dosing: 20-50% of normal dose

Contraindications

• Allergy to class/drug
• Afib/flutter associated with accessory bypass tract, e.g. WPW, Lown-Ganong-Levine syndrome
• Cardiogenic shock, hypotension, EF <30%
• 2nd or 3rd degree AV block, sick sinus syndrome

Adverse Reactions

Serious

• AV block
• MI
• Pulmonary edema

Common

• Hypotension
• Edema
• URI or flu-like symptoms
• Dizziness, headache
• Constipation

Pharmacology

• Half-life: 4-20 hours
• Metabolism: Hepatic- P450 CYP3A4, CYP1A2, CYP2C8, CYP2C9 and CYP2C18
• Excretion: Renal primarily. Not dialyzable

Mechanism of Action

• Inhibits L-type (slow) calcium channels, blocking influx of calcium into myocardial cells
• Reduces systemic vascular resistance, vasodiolates peripheral arteries

See Also

• Calcium channel blockers