Methemoglobinemia in aluminum phosphide ingestion: an effect of toxin or treatment?

March 21, 2011, 8:41 pm

★½☆☆☆

Methemoglobinemia in aluminum phosphide poisoning. Shadnia S et al. Hum Exp Toxicol 2011 Mar;30(3):250-3.

Abstract

As TPR noted in a recent post, aluminum phosphide (AlP) is an agent commonly used for suicide in developing countries.  It is a strong gastrointestinal irritant, causing rapid onset severe vomiting and abdominal pain.  Phosphine — a colorless, flammable, highly toxic gas — is formed when AlP comes into contact with moisture or acid.  Phosphine is also a potent cellular poison, impairing mitochondrial function by blocking cytochrome c oxidase, as well as producing free radicals and lipid peroxidation. AlP kills quickly from multi-system failure and cardiovascular collapse.

This brief report, from the Loghman Hakim Hospital Poison Center in Tehran, describes two patients who developed hemolysis and methemoglobinemia after reportedly ingesting aluminum phosphide tablets.  Both were lavaged with sodium bicarbonate and potassium permanganate.  Both died despite treatment with methylene blue or ascorbic acid.  Their conclusion is that: “Hemolysis and methemoglobinemia may complicate the course of phosphine poisoning that seems resistant to methylene blue or ascorbic acid”. They suggest considering hyperbaric oxygen therapy and exchange transfusion in these cases.

Reports of methemoglobinemia associated with aluminum phosphide are very rare; to my knowledge, there has been only one other case described in the literature.  Therefore, it is amazing that neither the authors nor the editors of Human and Experiment Toxicology saw fit to mention that potassium permanganate itself is a strong oxidizing and hemolytic agent, and can cause methemoglobinemia and hemolysis. Maybe the take-home lesson from this case should be that lavage with potassium permanganate provides more risk than benefit, and should not be recommended.

Related post:

What toxin causes a patient to spontaneously combust?

2 Comments:

  1. Pedantic Toxicologist Says:

    Oooh, you did it again: called an inorganic poison a toxin!

  2. Leon Says:

    P. Toxicologist:

    Yikes! It’s an old habit, and difficult to break. But you are right: all toxins are poisons, but not all poisons are toxins.