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Non-Dihydropyridine Calcium Channel Blocker Pregnancy: Avoid — animal data shows toxicity; limited human data

Diltiazem

Brand names: Tildiem, Dilzem

Adult dose

Dose: Oral: 60 mg TDS (standard release) or 90–180 mg BD (modified release). IV rate control: 0.25 mg/kg over 2 min, then 5–15 mg/h infusion
Route: Oral or IV
Frequency: TDS (standard); BD (MR); IV continuous
Max: 360 mg/day oral; IV infusion 15 mg/h
Rate control in AF/atrial flutter. NOT for acute rate control if severe LV dysfunction. Different brands are NOT interchangeable (different release profiles).

Paediatric dose

Dose: 0.25 mg/kg
Route: IV over 2 min
Frequency: May repeat once
Max: 20 mg IV dose
Concentration: 5 mg/mL mg/ml
Off-label in children; specialist paediatric cardiology only

Dose adjustments

Renal

No dose adjustment required

Hepatic

Reduce dose in significant hepatic impairment

Paediatric weight-based calculator

Off-label in children; specialist paediatric cardiology only

Clinical pearls

  • Tildiem, Dilzem SR, Angitil: different brands have different release profiles — do NOT substitute without prescribing by brand
  • Less negatively inotropic than verapamil — preferred in some patients with mild LV impairment
  • Useful for rate control in AF when beta-blocker not tolerated or contraindicated
  • IV diltiazem not available commercially in UK — check local pharmacy

Contraindications

  • Severe LV dysfunction or HFrEF
  • Second/third degree AV block (unless paced)
  • Sick sinus syndrome
  • WPW/accessory pathway
  • IV with beta-blocker IV

Side effects

  • Bradycardia
  • AV block
  • Hypotension
  • Oedema
  • Headache
  • Constipation
  • Flushing

Interactions

  • Beta-blockers — additive AV block/bradycardia (IV combination contraindicated)
  • Ciclosporin — increased ciclosporin levels
  • Simvastatin — myopathy (limit simvastatin to 40 mg)
  • Digoxin — increased levels
  • Carbamazepine — increased carbamazepine toxicity

Monitoring

  • Heart rate and ECG (PR interval)
  • Blood pressure
  • LFTs if prolonged use
  • Signs of AV block

Reference: BNFc; BNF; ESC AF Guidelines 2020; NICE NG196 AF guideline. Verify against your local formulary and the latest BNF before prescribing.

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