American Podiatric Medical Licensing Examination (APMLE) Part 1 Practice Test 2026 - Free APMLE Part 1 Practice Questions and Study Guide

Organophosphate poisoning inhibits acetylcholinesterase by phosphorylating the enzyme’s active site, causing a buildup of acetylcholine and overstimulation of cholinergic receptors. The antidote that can actually restore enzyme activity is pralidoxime, an oxime that cleaves the phosphate from the enzyme, reactivating acetylcholinesterase. This reactivation is most effective before the enzyme–phosphate complex ages, after which reactivation fails. Pralidoxime is used alongside atropine to address both nicotinic and muscarinic symptoms, but atropine alone doesn’t restore AChE function. Diazepam helps control seizures but doesn’t reverse enzyme inhibition, and epinephrine is a vasopressor rather than a specific antidote.