Which drug is a cholinesterase reactivator used to treat organophosphate toxicity?

• A. Glycopyrrolate
• B. Detomidine
• C. Pralidoxime
• D. Norepinephrine

Answer: (C)

Organophosphate poisoning shuts down acetylcholinesterase by phosphorylating its active site, causing a buildup of acetylcholine that overstimulates both muscarinic and nicotinic receptors. The only agent that directly reverses this inhibition is a cholinesterase reactivator, which binds to the inhibited enzyme and removes the organophosphate, restoring acetylcholinesterase activity. This reactivation helps reduce weakness, fasciculations, and other nicotinic symptoms, and also helps with muscarinic effects when used with supportive care. Timing is crucial because once the enzyme ages, reactivation is no longer possible. Pralidoxime (2-PAM) is the drug that does this reactivation; the other options are not enzyme reactivators—glycopyrrolate is an antimuscarinic to block muscarinic symptoms, while detomidine and norepinephrine are a sedative and a vasopressor, respectively.