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Xanthine bronchodilator (theophylline ethylenediamine) Pregnancy: Use with caution. Theophylline levels variable in pregnancy.

Aminophylline IV

Brand names: Aminophylline Injection

Adult dose

Dose: Loading (not on oral theophylline): 5 mg/kg IV over 20 min; maintenance: 0.5 mg/kg/hour
Route: IV infusion
Frequency: Loading dose then continuous maintenance
Max: Loading 500 mg; maintenance titrated to theophylline levels (target 10–20 mg/L)
Severe acute asthma (not responding to bronchodilators + steroids): 5 mg/kg IV over 20 min (OMIT loading if on oral theophylline — risk of toxicity). Maintenance 0.5 mg/kg/hour. Reduce dose in elderly, hepatic disease, heart failure.

Paediatric dose

Dose: 5 mg/kg
Route: IV
Frequency: Loading over 20 min; then maintenance
Max: Loading: 5 mg/kg (max 500 mg); maintenance: 1 mg/kg/hour (neonate) to 0.5 mg/kg/hour (child)
Concentration: 25 mg/ml
Loading: 5 mg/kg IV over 20 min (omit if on theophylline). Maintenance: neonates 0.16–1 mg/kg/hour; children 6 months–9 years: 1 mg/kg/hour; children 10–16 years: 0.8 mg/kg/hour. Therapeutic range: 10–20 mg/L.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Reduce dose by 50% in severe hepatic impairment (reduced clearance).

Paediatric weight-based calculator

Loading: 5 mg/kg IV over 20 min (omit if on theophylline). Maintenance: neonates 0.16–1 mg/kg/hour; children 6 months–9 years: 1 mg/kg/hour; children 10–16 years: 0.8 mg/kg/hour. Therapeutic range: 10–20 mg/L.

Clinical pearls

  • MAGICPAK trial: unclear benefit over standard care — use only for severe cases not responding
  • Narrow therapeutic index (10–20 mg/L) — regular plasma levels essential
  • Caffeinated drinks and smoking affect levels — enquire
  • Hypokalaemia common with IV aminophylline — monitor and correct
  • Increasingly less used as IV salbutamol and IV magnesium (2 g over 20 min) preferred

Contraindications

  • Porphyria
  • Pre-existing oral theophylline (omit loading dose)

Side effects

  • Nausea and vomiting (therapeutic)
  • Tachyarrhythmias (toxic)
  • Seizures (toxic — levels >25 mg/L)
  • Hypokalaemia
  • Palpitations

Interactions

  • Ciprofloxacin, erythromycin, cimetidine — increase theophylline levels (toxicity)
  • Rifampicin, phenytoin, carbamazepine, smoking — decrease theophylline levels
  • Beta-blockers — antagonise bronchodilator effect

Monitoring

  • Theophylline plasma level (6h post-loading, then 12-hourly)
  • ECG
  • Serum potassium

Reference: BNFc; BNF; BTS/SIGN Asthma Guidelines; BNFc. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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