Direct agonists Most direct agonists are resistant to acetylcholinesterase (AChE) login to view 2 more bullets Direct AgonistsUsesMechanism of ActionMethacholine• Challenge test for bronchial airway hyperactivity/asthma• Rapid onset of contraction of smooth muscles in the airways and increases tracheobronchial secretions• Slightly resistant to acetylcholine-esterase (AChE)Pilocarpine• Management of glaucoma• Contracts the pupillary sphincter (miosis) and ciliary muscle (improved accommodation)• Lowers intraocular pressure by reducing resistance to aqueous humor outflow• Resistant to AChEBethanechol• Acute postoperative and postpartum urinary retention• Neurogenic ileus• Causes bladder contractions which initiates urination• stimulates gastric motility and tone restoring peristalsis• Resistant to AChECarbachol• Lowers intraocular pressure treating glaucoma• Pupillary contraction• Stimulates muscarinic receptors causing miosis• Resistant to AChE Indirect Agonists (Cholinesterase Inhibitors) Mechanism of action login to view 2 more bullets Indirect AgonistUsesNotesPhysostigmine• Glaucoma• Atropine overdose orAtropa belladonna (deadly nightshade) ingestion• CNS penetration• Absorbs well on all bodily surfacesNeostigmine• Postoperative and neurogenic ileus and urinary retention• Myasthenia gravis• Reversal of neuromuscular junction blockade (postoperative)• No CNS penetrationPyridostigmine• Myasthenia gravis• No CNS penetrationEdrophonium• Diagnosis of myasthenia gravis• Ileus• Arrhythmias• Extremely short lived (5 - 15 min)Echothiophate• Glaucoma• Long-lasting (100 hours)• No CNS penetration• Insecticides: malathion is safe in humans but parathion is harmful and both can penetrate the CNS Cholinesterase Inhibitor Poisoning Cholinesterase poisoning symptoms login to view 9 more bullets Treatment login to view 2 more bullets