Theophylline toxicity

Background

• Still used in patients with debilitating brochospastic disease
• Studied for treatment of Acute Mountain Sickness and Contrast-Induced Nephropathy
• PO in elixir, extended release, or controlled release forms but absorption erratic
• IV as aminophylline
• Adenosine antagonism, Increase catecholamines, and Phosphodiesterase inhibition

Clinical Features

• Neurologic
  • Tremor
  • Agitation
  • Seizure
• Cardiovascular
  • Sinus Tachycardia
  • Atrial/Ventricular arrhythmias
  • Hypotension
• Metabolic
  • Hypokalemia
  • Metabolic Acidosis
  • Hyperthermia
  • Rhabdomyolysis
  • Hyperglycemia
• GI
  • Nausea/Vomiting

Workup

• ECG
• Chem
• CK
• Theophylline level

Management

• GI decontamination (Multidose Activated Charcoal, Whole Bowel Irrigation)
  • Considered in life-threatening overdose
    • contraindications: unsecured airway, nausea, vomiting, ileus, Bowel Obstruction, or need for emergent endoscopy
• Seizures
  • Lorazepam (Ativan) 1st line
  • Phenobarbital if lorazepam ineffective
  • Phenytoin (Dilantin) contraindicated as increases seizure in animal studies
• Cardiovascular
  • IV Fluids for hypotension
  • Beta blockers for tachyarrhymias
    • Controversial, involve a toxicologist
• Dialysis
  • Indicated in seizures, severe arrhythmias
  • Theophylline level >90mcg/ml in acute ingestion
  • Theophylline level >40mcg/ml in chronic ingestion
• Supportive care
  • Cardiac monitoring
  • Ondansetron (Zofran) for antiemetic
  • EEG for sedated and paralyzed patients

Disposition

• Immediate release
  • Home after 6 hours if
    • nontoxic
    • asymptomatic
    • and, normal vital sign
• Sustained release
  • Home after 12 hours if
    • nontoxic
    • asymptomatic
    • and, normal vital sign