Tricyclic Antidepressant Poisoning

Description

General Measures

Medicine Treatment

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T43.0 + (X41.99/X61.99/Y11.99)

DESCRIPTION

TCAs may be life threatening at relatively low doses. Cardiovascular and neurological impairment are the most serious consequences of TCA toxicity, and patients can deteriorate rapidly depending on the severity.

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Mild to moderate poisoning:

• Sedation
• Anticholinergic effects:
  • delirium,
  • tachycardia
  • urinary retention
  • dilated pupils
  • dry mouth

Severe Poisoning:

• Widened QRS duration, ventricular dysrhythmias
• Seizures
• Coma
• Pulmonary oedema
• Hypotension

GENERAL MEASURES

• Do a baseline ECG in all patients.
• ICU admission for ventilatory/circulatory support, when indicated. Be prepared to intubate symptomatic patients early.
• Discharge patients only when:
  • asymptomatic, or
  • mild symptoms/signs of toxicity and ECG has normalised for at least 24 hours.

MEDICINE TREATMENT

Tricyclic antidepressants delay gastric emptying, therefore activated charcoal may be effective for a longer period than usual.

Indications for serum alkalinisation:

• ventricular dysrhythmias,
• prolonged QRS >100 msec,
• hypotension unresponsive to fluids, or
• seizures.
• Sodium bicarbonate 8.4% solution, IV 1–2 mL/kg administered in bolus doses (Specialist consultation).
  • Aim to achieve a serum pH of 7.45–7.55.
  • Monitor acid-base status, serum potassium and sodium.
  • If sodium bicarbonate is unavailable or fluid restrictions limit intake, consider hyperventilation of intubated patients.

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In severe cases, inotropic support and anti-arrhythmics may be required (See: Cardiac dysrhythmias) in addition to serum alkalinisation. Hypotension is due to myocardial dysfunction and alpha-adrenergic vasodilation; be careful not to fluid overload the patient.

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For seizures or if sedation is required for restlessness: Treat with benzodiazepines - see: Status epilepticus.

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Note:
Phenytoin should be avoided (due to potential cardiotoxicity).

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Note:
Flumazenil is not recommended in any patient with mixed overdoses possibly including tricyclic antidepressants as it increases the risk of convulsions and dysrhythmias.

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Click here to access the pdf.

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Standard Treatment Guidelines and Essential Medicines List for South Africa, Adult Hospital Level, 2020-2024_Version 2.0_27 March 2025

Chapter 19 Poisoning_19.6.1 Tricyclic Antidepressant Poisoning