A 70-year-old man started on oxybutynin for overactive bladder is brought to the emergency department two days later with agitation, visual hallucinations, dry skin, and dilated sluggish pupils. Which drug is most appropriate for reversal of his central anticholinergic syndrome?
- A Neostigmine
- B Pralidoxime
- C Physostigmine ✓
- D Pyridostigmine
Correct answer: C. Physostigmine
Explanation
Physostigmine is a tertiary amine cholinesterase inhibitor that crosses the blood-brain barrier, so it reverses both central and peripheral features of antimuscarinic toxicity. Neostigmine and pyridostigmine are quaternary ammonium compounds that do not enter the CNS and would only address peripheral signs while leaving the delirium untouched. Pralidoxime reactivates phosphorylated cholinesterase in organophosphate poisoning and has no role here because the enzyme is not covalently inhibited.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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