Only anticholinergic commonly used to reverse the action of Neuromuscular Blocker?
Correct Answer: Neostigmine
Description: Ans. d (Neostigmine) (Ref. KD Trip at hi, Pharmacology, 6th ed. 104)Postoperative decurarization by neostigmine 0.5-2.0 mg i.v., preceded by atropine to block muscarinic effects, rapidly reverses muscle paralysis induced by competitive NM blockers.NEOSTIGMINE# A anticholinesterase drug# A cholinomimetic drug# Neostigmine (cholinomimetic) and its congeners improve muscle contraction:- By allowing ACh released from prejunctional endings to accumulate and act on receptors over a larger area, and- By directly depolarizing the end plate.# Does not penetrate BBB or cornea, hence has no CNS effects.# Poor oral absorption# Pyridostimine is an alternative, which needs less frequent dosing.# Clinical Uses of Anticholinesterases (Neostigmine)- Postoperative ileus (Rarely, in resistant cases, medical therapy with an adrenergic blocking agent in association with cholinergic stimulation, e.g. neostigmine , may be used, provided that an intraperitoneal cause has been excluded.)- Postoperative urine retention- Postoperative decurarization- Cobra bite- Belladonna poisoning- TCA toxicity- Alzheimer's disease (Riastigmine, Galantamine, Donepezil, Tacrine)Comparison between Physo and NeostigmineFeaturesPhysostigmineNeostigmine1. SourceNatural alkaloid from Calabar beanSynthetic2. ChemistryTertiary amine derivativeQuarternary ammonium compound3. Oral absorptionGoodPoor4. CNS actionsPresentAbsentS. Applied to eyePenetrates corneaPoor penetration6. Direct action on CholinoceptorsAbsentPresent7. Prominent effect onAutonomic effectorsSkeletal muscles8. Important useMiotic (glaucoma)Myasthenia gravis9. Dose0.5-1 mg oral/parenteral; 0.1-1.0% eye drops0.5-2.5 mg i.m./s.c.; 15-30 mg orally10. Duration of actionSystemic 4-6 hrs; In eye 6 to 24 hrs3-4 hrs.
Category:
Anaesthesia
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