Although not as commonly used for their original purpose, tricyclic antidepressants (TCAs) remain in use for the treatment of depression and other conditions. 

• Tricyclic antidepressant overdose produces sedation, unconsciousness, and seizures.  Tachycardias, including wide complex tachycardias, and hypotension are common.
• Patients who have overdosed on TCAs can deteriorate rapidly.  Urgent transport with appropriate preparation should be strongly considered.
• As with most poisonings or overdoses, care for TCA toxicity is primarily supportive.  Protect the airway, provide supplemental oxygen, maintain effective ventilation, and support blood pressure as necessary.
• ECG monitoring can be helpful in identifying cardiac rhythm disturbances common to TCA overdose.  Consider ACP intercept where available.
• Consider the possibility of co-ingestion of other medications or substances.  Care more generally for the patient than for any particular poison.

• Patients who have overdosed on TCAs are frequently hypotensive.  Fluid resuscitation should be initiated in patients who are significantly hypotensive; unmanaged hypotension is a primary cause of mortality in these patients.
• Sodium bicarbonate should be considered, in consultation with CliniCall, when the QRS interval exceeds 100 ms or the QRS morphology is grossly distorted.
• As a general rule, antiarrhythmics should be avoided in TCA overdose: their interactions with a disordered heart are unpredictable, and most have been poorly studied.  Magnesium may be an acceptable antiarrhythmic in the context of cardiac arrest, but should only be given in consultation with CliniCall. 

• Tricyclic antidepressant overdoses carries several important clinical consequences; the most significant is the blockade of fast sodium channels in the heart.
• The clinical course of a TCA poisoning is unpredictable due to complexities with uptake from the gastrointestinal tract, bioavailability, and drug metabolism.  Patients may initially appear well, but deteriorate rapidly and without warning.
• Signs of TCA poisoning typically include sedation, but may also feature confusion, delirium, and hallucinations.  Anticholinergic effects, such as hyperthermia, flushing, and dilated pupils are common.  Hypotension is the most ominous finding; the majority of patients who die from TCA overdose do so as a result of refractory, uncorrectable hypotension.
• ECG findings in TCA overdose include:
  • QRS > 100 ms
  • Deep S waves in leads I, aVL
  • Tall R waves in lead aVR
  • Tachycardias, including sinus tachycardia

Poisoning/Overdose