SNRI Toxicity

Background

• Inhibits reuptake of serotonin, norepinephrine and small effect on dopamine
  • Examples: venlafaxine, duloxetine
• Adverse effects similar to SSRIs
• Venlafaxine (Effexor)
  • Can produce mild to moderate hypertension
• Duloxetine (Cymbalta)
  • Nausea, vomiting, dizziness

Clinical Features

• Sympathomimetic: tachycardia, hypertension, diaphoresis, tremor, mydriasis
  • Secondary to inhibition of norepinephrine reuptake
• Sedation
• Seizures
  • More common than with SSRI toxicity
• Rhabdomyolysis
  • 25% occur without seizures
• ECG
  • Most common abnormality: sinus tachycardia
  • May see QRS widening or QT prolongation

Evaluation

• Suggestive history with appropriate clinical features

Management

• Cardiac monitoring
• Supportive Care: IV fluids for hypotension, Benzodiapazines for seizures
• Consider single dose activated charcoal

Disposition

• Admit all symptomatic patients to a monitored bed
• Monitor for 6 hours, longer for extended-release preparations

See Also

• SSRI Toxicity

References

• Mills K. Atypical Antidepressants, Serotonin Reuptake Inhibitors, and Serotonin Syndrome In: Tintinalli's Emergency Medicine. 7th ed. McGraw Hill. 2011:1198-2002