Question

Which of the following is an antidote for organophosphorus poisoning?

• A. Pralidoxime
• B. Naloxone
• C. Physostigmine
• D. Sodium thiosulfate

Hint:

In organophosphorus poisoning, pralidoxime combined with atropine is used to reverse both muscarinic and nicotinic effects by reactivating acetylcholinesterase and blocking acetylcholine receptors.

Answer 1

The Correct Option is A

Organophosphorus compounds inhibit acetylcholinesterase, causing accumulation of acetylcholine at nerve synapses, leading to overstimulation of cholinergic receptors and symptoms of poisoning such as salivation, lacrimation, muscle twitching, and respiratory distress. - Pralidoxime (2-PAM) is a specific antidote that reactivates acetylcholinesterase by cleaving the phosphate-enzyme bond formed by organophosphates, thus restoring enzyme activity.
- It is most effective if given early before the "aging" of the enzyme-inhibitor complex occurs.
- Naloxone is an opioid antagonist used in opioid overdose, not in organophosphorus poisoning.
- Physostigmine is an acetylcholinesterase inhibitor and is contraindicated here as it would worsen cholinergic crisis.
- Sodium thiosulfate is used in cyanide poisoning, not organophosphorus poisoning.
Thus, pralidoxime is the correct antidote for organophosphorus poisoning.