What is the treatment for a Selective Serotonin Reuptake Inhibitor (SSRI) overdose?

Treatment of SSRI Overdose

The treatment of SSRI overdose requires immediate hospital-based care with discontinuation of all serotonergic agents, supportive care, and continuous cardiac monitoring, particularly for signs of serotonin syndrome and QT interval prolongation. 1

Initial Assessment and Management

• Immediate Discontinuation: Stop all serotonergic medications immediately
• Supportive Care:
  • Airway management and oxygen supplementation as needed
  • IV fluid administration for hemodynamic support
  • Continuous cardiac monitoring for QT prolongation and arrhythmias
  • Vital sign monitoring with special attention to temperature, heart rate, and blood pressure

Management of Serotonin Syndrome

Serotonin syndrome is a potentially life-threatening condition characterized by:

1. Mental status changes: Confusion, agitation, anxiety
2. Neuromuscular hyperactivity: Tremors, clonus, hyperreflexia, muscle rigidity
3. Autonomic hyperactivity: Hypertension, tachycardia, arrhythmias, tachypnea, diaphoresis, shivering, vomiting, diarrhea

Treatment of Serotonin Syndrome

• Benzodiazepines: First-line for managing agitation and tremors
• Temperature control: For hyperthermia (temperature >38°C)
• Avoid physical restraints: May exacerbate isometric contractions, worsening hyperthermia and lactic acidosis 1
• Severe cases (temperature >41.1°C):
  • Emergency sedation
  • Neuromuscular paralysis
  • Intubation and mechanical ventilation
  • ICU admission (approximately 25% of cases require this level of care) 1
• Serotonin2A antagonists: Cyproheptadine may be considered in severe cases 1

Cardiac Monitoring

• QT interval monitoring: Particularly important with citalopram overdose, which has been significantly associated with QT prolongation 2
• ECG monitoring: Recommended for all SSRI overdoses, but especially critical for citalopram 2
• Extended monitoring: Continue for at least 24 hours as QTc prolongation may develop after initial presentation 3

Laboratory and Diagnostic Testing

Consider the following based on clinical presentation:

• Complete blood count
• Electrolytes (watch for hyponatremia)
• Renal and liver function tests
• Arterial blood gas (check respiratory status and metabolic acidosis)
• Creatine kinase (for rhabdomyolysis)
• Coagulation studies
• Toxicology screens
• ECG

Special Considerations

• Mortality risk: Approximately 11% in severe serotonin syndrome cases 1
• Complications to monitor: Rhabdomyolysis, metabolic acidosis, elevated liver enzymes, renal failure, seizures, and disseminated intravascular coagulation 1
• Drug interactions: Be vigilant about other medications that may worsen serotonin syndrome, particularly:
  • MAOIs (absolute contraindication)
  • Other serotonergic drugs (opioids, stimulants, other antidepressants)
  • Medications that prolong QT interval 1, 4

Prognosis

The prognosis for SSRI overdose with appropriate treatment is generally good. In one retrospective study, there were no deaths reported in 313 SSRI-poisoned dogs, suggesting relatively low toxicity compared to other antidepressant classes like tricyclics 5.

Common Pitfalls to Avoid

1. Failure to recognize serotonin syndrome: Use Hunter criteria for diagnosis (more sensitive and specific than Sternbach criteria) 1
2. Inappropriate use of physical restraints: Can worsen hyperthermia and increase mortality
3. Overlooking cardiac monitoring: Especially with citalopram overdose
4. Missing drug interactions: Particularly with MAOIs or other serotonergic medications
5. Inadequate duration of monitoring: QT prolongation may develop hours after initial presentation

Remember that SSRIs are generally safer in overdose than tricyclic antidepressants, but they still require prompt recognition and management of potential complications, particularly serotonin syndrome and QT interval prolongation.