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Non-Dihydropyridine Calcium Channel Blocker Pregnancy: Caution — crosses placenta; used for fetal tachyarrhythmia under specialist supervision

Verapamil

Brand names: Securon, Univer

Adult dose

Dose: SVT (IV): 5–10 mg IV over 2 min; may repeat 5 mg after 5–10 min. Oral: 40–120 mg TDS
Route: IV or Oral
Frequency: IV: slow bolus; Oral: TDS
Max: IV: 20 mg total; Oral: 480 mg/day
NEVER use IV verapamil if patient on beta-blocker — risk of fatal asystole/complete heart block. Contraindicated in WPW syndrome.

Paediatric dose

Dose: 0.1 mg/kg
Route: IV slow bolus (over 2 min)
Frequency: Single dose, repeat once if needed
Max: 5 mg per dose
Concentration: 2.5 mg/mL mg/ml
Do NOT use IV verapamil in infants <1 year (risk of cardiac arrest). Not in neonates.

Dose adjustments

Renal

No dose adjustment required

Hepatic

Reduce dose significantly in hepatic impairment (extensive hepatic metabolism)

Paediatric weight-based calculator

Do NOT use IV verapamil in infants <1 year (risk of cardiac arrest). Not in neonates.

Clinical pearls

  • Verapamil is the most negatively inotropic CCB — avoid in HFrEF
  • Digoxin levels rise by up to 70% when verapamil added — halve digoxin dose
  • In AF with WPW: verapamil causes AF degeneration to VF via accessory pathway — absolutely contraindicated
  • Oral verapamil may be used for rate control in AF in certain patients without HF

Contraindications

  • Second/third degree AV block
  • Sick sinus syndrome (unless paced)
  • Systolic dysfunction/HF with reduced EF
  • WPW or accessory pathway AF (can cause VF)
  • IV use with IV beta-blocker (asystole risk)
  • Hypotension

Side effects

  • Constipation (most common oral SE)
  • Bradycardia
  • Hypotension
  • AV block
  • Oedema
  • Flushing
  • Nausea

Interactions

  • Beta-blockers IV — asystole (contraindicated IV)
  • Digoxin — increased digoxin levels by 50–75%
  • Simvastatin — myopathy risk (limit simvastatin to 20 mg)
  • Ciclosporin — increased ciclosporin toxicity
  • Lithium — neurotoxicity

Monitoring

  • ECG (PR interval, heart rate)
  • Blood pressure
  • Digoxin levels if co-prescribed
  • Signs of AV block

Reference: BNFc; BNF; ESC AF Guidelines 2020; ACC/AHA Guideline on Atrial Fibrillation. Verify against your local formulary and the latest BNF before prescribing.

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