Toxicology: aluminium phosphide: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Toxicology: aluminium phosphide

Sample item

A farmer who swallowed grain-preservative tablets develops a garlic odour on the breath, refractory hypotension and metabolic acidosis. Which mechanism best explains the shock?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Phosphine inhibition of mitochondrial cytochrome oxidase causing cellular hypoxia and myocardial depression

Aluminium phosphide releases phosphine gas in the stomach, which inhibits cytochrome c oxidase and generates oxidative injury, producing severe myocardial dysfunction, vasodilation and refractory shock. There is no specific antidote, and treatment is early decontamination, supportive care, and vasopressors with early intensive care. It is a frequent cause of fatal suicidal poisoning in India.

Option by option

  • A. Phosphine inhibition of mitochondrial cytochrome oxidase causing cellular hypoxia and myocardial depression (correct)

    Cytochrome oxidase inhibition by phosphine explains the shock and acidosis.

  • B. Persistent opening of sodium channels

    Sodium channel persistent opening describes pyrethroids and veratrum alkaloids.

  • C. Oxidation of haemoglobin to methaemoglobin

    Methaemoglobin formation describes nitrites and dapsone.

  • D. Irreversible inhibition of acetylcholinesterase

    Acetylcholinesterase inhibition describes organophosphates and carbamates.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Phosphine inhibition of mitochondrial cytochrome oxidase causing cellular hypoxia and myocardial depression. Aluminium phosphide releases phosphine gas in the stomach, which inhibits cytochrome c oxidase and generates oxidative injury, producing severe myocardial dysfunction, vasodilation and refractory shock.

Why is "Persistent opening of sodium channels" not the answer?

Sodium channel persistent opening describes pyrethroids and veratrum alkaloids.

Why is "Oxidation of haemoglobin to methaemoglobin" not the answer?

Methaemoglobin formation describes nitrites and dapsone.

Why is "Irreversible inhibition of acetylcholinesterase" not the answer?

Acetylcholinesterase inhibition describes organophosphates and carbamates.

What concept does this question test?

It tests Toxicology: aluminium phosphide in Pharmacology. There is no specific antidote, and treatment is early decontamination, supportive care, and vasopressors with early intensive care. It is a frequent cause of fatal suicidal poisoning in India.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Toxicology: aluminium phosphide?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.