The Poison Review

Intravenous fat emulsion to reverse haemodynamic instability from intentional amitriptyline overdose. Engels PT, Davidow JS. Resuscitation 2010;81:1037-1039.

Abstract

This case report, from Edmonton Alberta, describes a 27-year-old man who ingested — by history — 4.25 g of amitriptyline.  In the emergency department he was unresponsive with a GCS of 3, BP 67/40, and QRS interval 240 msec.  On arrival he had two tonic-clinic seizures and was intubated.  Despite treatment with sodium bicarbonate, pressors, and benzodiazepines, he suffered episodes of pulseless ventricular tachycardia and remained pressor-dependent approximately 8 hours after ingestion  At that time the treating team decided to administer intravenous fat emulsion therapy.  After the initial bolus, pressors were rapidly weaned and eventually discontinued. Urine toxicology screen was positive for tricyclics.

It is, of course, impossible to draw any firm conclusions from this case report, especially since the patient “turned around” so long after ingestion and had received multiple interventions.  Although there have been no previous case reports of lipid rescue use in tricyclic antidepressant toxicity, there have been supportive studies in rat and rabbit models.

The authors point out that there are several possible mechanisms that might explain a beneficial effect of lipid rescue in TCA overdose.  Since TCAs are lipophilic, fat emulsion might provide a “lipid sink” that would sequester the drug and accelerate removal from tissues.  Lipids might also provide an energy source for myocardial cells.  Finally, they might have a direct effect on calcium channels.