Tricyclic antidepressant overdose

Question 1

What are the symptoms of a TCA overdose?

Answer 1

Arrhythmias - Na channel blockade
Hypotension - vasodilation and decreased reuptake of chatecholamines
Seizures
Reduced GCS
Anticholinergic toxidrome - Tachy, pyrexia, myoclonus, retention, decreased bowel sounds

Question 2

How might a TCA overdose be diagnosed?

Answer 2

History and clinical presentation
Typical ECG findings - Tachy, right axis deviation, broad QRS (>4 small squares = increased arrhythmia risk), prolonged QT

Question 3

How would you manage a TCA overdose?

Answer 3

A-E supportive managment
Activated charcoal may be used for up to 24hrs
If seizures, broad qrs or hypotensive not responding to fluids, give bicarb
Bicarb alkalinises blood and increases protein binding of the drug which reduces renal reabsorption
Lidocain, magnesium or intralipid for arrhythmias -DO NOT GIVE AMIODARONE DUE TO RISK OF PROLONGING QT FURTHER

Question 4

Which drugs are cleared by RRT?

Answer 4

Valproate
Aspirin
Lithium
Aminoglycosides
Carbemazepine
Theophyllines
Ethylene glycol
Metformin
Methanol
Methotrexate