Theophylline toxicity

Background

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

Clinical Features

1. Neurologic
   1. Tremor
   2. Agitation
   3. Seizure
2. Cardiovascular
   1. Sinus Tachycardia
   2. Atrial/Ventricular arrhythmias
   3. Hypotension
3. Metabolic
   1. Hypokalemia
   2. Metabolic Acidosis
   3. Hyperthermia
   4. Rhabdomyolysis
   5. Hyperglycemia
4. GI
   1. Nausea/Vomiting

Workup

1. ECG
2. Chem
3. CK
4. Theophylline level

Management

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

Disposition

1. Immediate release
   1. Home after 6 hours if
      1. nontoxic
      2. asymptomatic
      3. and, normal vital sign
2. Sustained release
   1. Home after 12 hours if
      1. nontoxic
      2. asymptomatic
      3. and, normal vital sign

References

Tintinalli