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Theophylline

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Theophylline toxicity

Clinical features

Neurological

  • fits
  • uncontrolled fits may lead to hyperthermia and rhabdomyolysis

Cardiovascular

  • tachyarrhythmias
    • supraventricular
    • ventricular
  • cardiovascular collapse

Metabolic

  • hypokalaemia
  • hypomagnesaemia
  • hyperglycaemia
  • hypophosphataemia
  • hypercalcaemia
  • respiratory alkalosis

Treatment

  • gastric lavage followed by activated charcoal
    • if slow release preparations have been taken gastric lavage may be useful for several hours after ingestion
    • theophylline undergoes significant enterohepatic circulation and therefore multiple doses of activated charcoal may be useful to enhance elimination
  • fits
    • benzodiazepines agents of choice
    • phenobarbitone for refractory seizures
    • phenytoin contraindicated - can exacerbate theophylline-induced fits
  • supraventricular tachycardias
    • ß1-cardioselective ß blocker (eg metoprolol, esmolol)
      • Use with extreme caution in patients with obstructive airways disease and avoid if bronchospasm present
    • calcium channel blockers
  • ventricular arrhythmias
    • lignocaine and other standard agents suitable
  • aggressive electrolyte replacement for patients with arrhythmias
    • bear in mind that hypokalaemia is due to intracellular shift not total body loss
  • refractory hypotension: non-selective ß blockers (eg propranolol) have been used
  • severe nausea: ondansetron
  • charcoal haemoperfusion or haemodialysis (less effective). Indications:
    • refractory fits, hypotension or unstable arrhythmias or
    • plasma level >100mg/l 2 h after acute ingestion and after initial charcoal therapy
    • plasma level >50 mg in chronic ingestion
    • plasma concentration >35 mg/l 2 h after acute ingestion with clinical instability or high risk of adverse outcome or prolonged intoxication. Factors associated with high risk:
      • chronic intoxication
      • intolerance of oral charcoal
      • intractable vomiting
      • impaired theophylline metabolism
        • congestive cardiac failure
        • cirrhosis
        • severe hypoxaemia
      • increased susceptibility to cardiovascular toxicity and fits
      • respiratory failure

Further reading

Mokhlesi B et al. Adult toxicology in critical care. Part II: specific poisonings. Chest 2003; 123:897-922

©Charles Gomersall, October, 2009 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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