A 22-year-old woman is brought to the emergency department with agitation, flushing, dry skin, urinary retention and a heart rate of 140/min after consuming an unknown plant extract. The resident decides to give a drug that will reverse both the central and peripheral manifestations. Which agent is most appropriate?
- A Neostigmine
- B Pralidoxime
- C Physostigmine ✓
- D Pyridostigmine
Correct answer: C. Physostigmine
Explanation
Physostigmine is a tertiary amine carbamate cholinesterase inhibitor that crosses the blood-brain barrier, so it reverses the central anticholinergic syndrome as well as peripheral signs such as tachycardia and urinary retention. Neostigmine and pyridostigmine are quaternary ammonium compounds that cannot cross the blood-brain barrier and therefore treat only peripheral features. Pralidoxime reactivates phosphorylated enzyme in organophosphate poisoning and has no role here.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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