Most commonly used cholinesterase regenerator at NM junction is ?: (A) Pralidoxime, (B) Obidxime, (C) Diacetyl monoxime, (D) Edrophonium
Answer is A. Ans. is 'a' i.e., Pralidoxime Pralidoxime is most commonly used cholinesterase reactivater. OXIMES Oximes Pralidoxime 2-PAM, obidoxime and diacetyl-monoxime (DAM)] are used in organophosphate poisoning. o Oximes acts by reactivating cholinesterase enzyme. Mechanism of action In organophosphate poisoning esteratic site of cholinesterase is phosphorylated and anionic site is free. Phosphorylated cholinesterase reacts very slowly with water. However, if more reactive OH groups in the form of oximes are provided, reactivation occurs more than a million time faster. Oximes attach to anionic site and provide more reactive OH groups. Oximes are ineffective in Carbamates poisoning. Pralidoxime is contraindicated in carbamates poisoning, because not only it does not reactivate carbamylated enzyme, it has weak anti-chE activity of its own. Remember Obidoxime is more potent than pralidoxime. Pralidoxime and obidoxime are lipid insoluble, while diacetyl-monoxime (DAM) is lipid soluble so it can cross BBB and regenerate AChE in brain. Atropine is used in both organophosphate and carbamate anticholinesterase poisoning.