Makindo Medical Notes

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Selective Serotonin Reuptake Inhibitors (SSRIs) are commonly prescribed antidepressants that increase serotonin levels in the central nervous system. While generally safe when used as directed, SSRIs can lead to significant toxicity in cases of overdose or adverse reactions.

About

• Selective Serotonin Reuptake Inhibitor (SSRI) toxicity.
• Commonly used antidepressants that increase serotonin levels in the CNS.
• SSRIs are generally less cardiotoxic than tricyclic antidepressants (TCAs). Common SSRIs include fluoxetine, citalopram, and venlafaxine.

Clinical Presentation

• Central Nervous System: Drowsiness in severe overdose, potential for seizures (especially with venlafaxine), and symptoms of serotonin syndrome.
• Gastrointestinal Symptoms: Nausea, vomiting, and diarrhoea.
• Neurological Symptoms: Tremor, agitation.
• Cardiovascular Effects: Hypertension, tachycardia.

Serotonin Syndrome

• Occurs due to excessive serotonin accumulation in the CNS.
• Symptoms include confusion, agitation, hyperthermia, hyperreflexia, clonus, and autonomic instability.
• Can be life-threatening if not promptly treated.

Differential Diagnoses

• Serotonin Syndrome vs. Neuroleptic Malignant Syndrome.
• Overdose of other serotonergic agents.
• Other causes of altered mental status and autonomic instability.

Investigations

• Vital Signs: Monitor blood pressure, heart rate, respiratory rate, and temperature.
• Electrocardiogram (ECG): To assess for any cardiac conduction abnormalities.
• Laboratory Tests:
  • Complete Blood Count (CBC).
  • Electrolytes, Urea & Electrolytes (U&E).
  • Liver Function Tests (LFTs).
  • Serum drug levels if available.
• Neurological Assessment: To identify signs of serotonin syndrome.

Management

• Activated Charcoal: Administer if the overdose occurred within the past hour and if more than 10 tablets were ingested.
• Supportive Care: Monitor vital signs and manage symptoms as needed. Patients are usually medically stable within 12 hours.
• For Serotonin Syndrome:
  • Use benzodiazepines for agitation and seizures.
  • Consider cyproheptadine, a serotonin antagonist, if symptoms are severe.
  • Provide supportive measures for autonomic instability.
  • Consult with a toxicologist if needed.
• Anticonvulsants: For seizures, especially with venlafaxine overdose.
• Continuous Cardiac Monitoring: Especially important if there's ingestion of multiple pills or co-ingestion with other cardiotoxic substances.
• Psychiatric Evaluation: Once medically stable, to assess for underlying mental health issues contributing to overdose.

Prognosis

• Most patients recover fully with prompt and appropriate treatment.
• Complications can occur if serotonin syndrome is not recognized and treated promptly.
• Mild toxicity may resolve with supportive care alone.
• Severe toxicity can be life-threatening, emphasizing the importance of early intervention.

Prevention

• Educate patients on the safe use of SSRIs and the risks of overdose.
• Implement medication reconciliation to avoid co-prescription of other serotonergic agents.
• Ensure proper storage of medications to prevent accidental or intentional overdose.
• Regular follow-up appointments to monitor adherence and address any side effects or concerns.

Conclusion

Selective Serotonin Reuptake Inhibitor (SSRI) toxicity is a manageable condition with appropriate medical intervention. Early recognition of symptoms, especially serotonin syndrome, and prompt supportive care are critical for favorable outcomes. Prevention strategies, including patient education and careful medication management, play a vital role in reducing the incidence of SSRI overdose and associated complications.

References

• UpToDate. Selective Serotonin Reuptake Inhibitor (SSRI) Overdose. Available at: https://www.uptodate.com
• Mayo Clinic. SSRI Overdose. Available at: https://www.mayoclinic.org
• American Association of Poison Control Centers (AAPCC). SSRI Overdose. Available at: https://www.aapcc.org
• National Institutes of Health (NIH). Serotonin Syndrome. Available at: https://www.ncbi.nlm.nih.gov
• American Society of Health-System Pharmacists (ASHP). SSRI Toxicity Management Guidelines. Available at: https://www.ashp.org