What are the toxic levels of Lexapro (escitalopram)?

Toxic Levels of Lexapro (Escitalopram)

There is no established specific toxic blood level for escitalopram, but overdoses can cause serious cardiac complications including QT prolongation, wide complex tachyarrhythmias, and torsade de pointes, as well as seizures and altered mental status including coma. 1

Clinical Manifestations of Escitalopram Toxicity

Escitalopram overdose can present with several concerning clinical manifestations:

Cardiovascular Effects

• QRS and QTc interval prolongation
• Wide complex tachyarrhythmias
• Torsade de pointes
• Hypertension (most common)
• Rarely hypotension, especially with co-ingestants including alcohol 1

Neurological Effects

• Seizures (which may be delayed)
• Altered mental status including coma 1
• Serotonin syndrome (especially with multiple proserotonergic drug ingestion) 2

Comparative Toxicity

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

• In a comparative study of 374 citalopram and 421 escitalopram overdoses, more serious outcomes were associated with citalopram overdoses (p<0.001)
• Seizures were significantly more common with citalopram than escitalopram (30 vs. 1, p<0.001)
• QTc prolongation occurred in 14 citalopram cases and 7 escitalopram cases (p=0.109) 3

Case Reports of Fatal Overdoses

A case report documented a fatal overdose involving escitalopram with blood concentration of 65.5 mg/L, in combination with mirtazapine (20.3 mg/L) and valproic acid (417 mg/L) 4. This suggests that high blood concentrations in the range of 65 mg/L may be potentially lethal, especially when combined with other medications.

Management of Escitalopram Overdose

For patients with suspected escitalopram overdose:

1. Cardiac monitoring is essential:

   • Prolonged cardiac monitoring is recommended due to arrhythmia risk 1
   • Monitor for QT prolongation and arrhythmias

2. Gastrointestinal decontamination:

   • Consider activated charcoal for patients who present early after overdose 1
   • For pediatric patients, use non-sorbitol containing activated charcoal products 5

3. Supportive care:

   • Establish an open airway and provide ventilatory support as needed 5
   • Monitor for seizures and have anticonvulsant therapy available

4. Antidote considerations:

   • No specific antidote exists for escitalopram toxicity
   • Flumazenil should be avoided in mixed overdoses involving escitalopram due to risk of seizures 5

5. Expert consultation:

   • Contact a poison center (1-800-222-1222) or medical toxicologist for overdose management recommendations 1

Special Considerations

• Dose-response relationship: There is an association between increasing dose and severity of outcome for escitalopram (p=0.011) 3
• Pediatric patients: In children under 6 years old, even small ingestions can cause toxicity including drowsiness, nausea/vomiting, and tachycardia 3
• Drug interactions: Risk of serotonin syndrome is increased when combined with other serotonergic medications 2

Conclusion

While there is no established specific toxic blood level for escitalopram, clinical toxicity can manifest with serious cardiac complications, seizures, and altered mental status. Prompt recognition and management of these complications, along with supportive care and expert consultation, are essential for optimal outcomes in escitalopram overdose.