A patient with severe organophosphate poisoning presents with SLUDGE features and is treated with atropine and pralidoxime (2-PAM). Pralidoxime is most effective when given within:

• A 24–48 hours
• B 6 hours (before 'aging' of the acetylcholinesterase-OP complex occurs) ✓
• C 72 hours
• D 12 hours

Explanation

Pralidoxime (2-PAM) reactivates acetylcholinesterase by nucleophilically attacking and removing the organophosphate group from the enzyme's serine active site. However, 'aging' — an irreversible covalent rearrangement of the OP-enzyme complex — occurs within hours of exposure (typically within 6 hours for most OPs, though the exact timing varies by agent). After aging, the enzyme cannot be reactivated. This is why early administration of pralidoxime (within the first few hours, ideally) is essential for efficacy.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.