carbachol
Summary
Direct-acting cholinergic agonist with both muscarinic and nicotinic activity; resistant to acetylcholinesterase. Used topically to induce miosis in glaucoma and during ocular surgery.
Detail
Carbachol is a synthetic choline ester that activates both muscarinic and nicotinic ACh receptors and resists hydrolysis by acetylcholinesterase, giving it a longer duration than acetylcholine. Clinically used as an ophthalmic agent for miosis during cataract surgery and to lower intraocular pressure in open-angle glaucoma by contracting the ciliary muscle and opening the trabecular meshwork. Systemic adverse effects (rare with topical use) follow SLUDGE: salivation, lacrimation, urination, defecation, GI cramping, emesis, plus bronchospasm and bradycardia. Contrast with bethanechol (M3-selective, urinary/GI retention) and pilocarpine (glaucoma, xerostomia). Boards: 'carbachol = carbamoylcholine, resists AChE.'
Sources
- First Aid for USMLE Step 1 2024
- Sketchy Pharmacology
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