What is a toxic dose of Lexapro (escitalopram)?

Toxic Dose of Lexapro (Escitalopram)

Any dose of Lexapro (escitalopram) above the maximum therapeutic dose of 20 mg/day should be considered potentially toxic, with severe toxicity typically occurring at doses exceeding 600 mg (30 times the maximum daily dose).

Understanding Escitalopram Toxicity

Escitalopram is a selective serotonin reuptake inhibitor (SSRI) with a relatively favorable safety profile compared to other antidepressants. However, in overdose situations, it can cause significant toxicity.

Signs and Symptoms of Toxicity

Overdoses of escitalopram can manifest with several concerning symptoms:

• Cardiovascular effects:

  • QTc interval prolongation
  • Wide complex tachyarrhythmias
  • Torsade de pointes
  • Hypertension (most common)
  • Rarely hypotension 1

• Neurological effects:

  • Seizures (which may be delayed)
  • Altered mental status including coma
  • Serotonin syndrome (especially with co-ingestion of other serotonergic drugs) 1

Comparison with Citalopram

Escitalopram appears to be less toxic than its racemic parent compound citalopram in overdose:

• Seizures are significantly more common with citalopram overdoses (30 vs. 1 in a comparative study)
• Tremor is more frequent with citalopram (32 vs. 13)
• QTc prolongation occurs with both medications but may be less common with escitalopram 2

Toxic Dose Thresholds

While specific toxic thresholds vary by individual factors, research indicates:

• Therapeutic serum concentration range: 9-200 ng/mL
• Fatal overdoses have been associated with serum concentrations as high as 7300 ng/mL 3
• Severe toxicity is more likely with doses exceeding 600 mg in adults 3

Management of Escitalopram Overdose

1. Initial management:

   • Gastrointestinal decontamination with activated charcoal should be considered in patients who present early after overdose 1
   • Contact poison control center (1-800-221-2222) for management recommendations 1

2. Monitoring:

   • Prolonged cardiac monitoring is recommended due to arrhythmia risk 1
   • Monitor for delayed seizures
   • Watch for signs of serotonin syndrome (altered mental status, autonomic instability, neuromuscular abnormalities)

3. Treatment:

   • Supportive care is the mainstay of treatment
   • Treat seizures if they occur
   • Manage cardiac arrhythmias as needed
   • Consider cyproheptadine for serotonin syndrome

Risk Factors for Severe Toxicity

• Co-ingestion of other serotonergic medications
• Pre-existing cardiac conditions
• Delayed presentation after overdose 3
• Hepatic impairment (which may slow metabolism)

Special Populations

• In children under 6 years old, even small overdoses can cause toxicity including drowsiness, nausea/vomiting, and tachycardia, though seizures appear to be rare in this age group 2
• Elderly patients may be more susceptible to QTc prolongation and should be monitored closely

Prevention of Severe Outcomes

Early presentation to medical care is critical for preventing fatal outcomes from escitalopram overdose. The delayed presentation likely contributes significantly to mortality in severe cases 3.