Autonomic NS 9: Choline Esters & Cholinomimetic alkaloids (parasympathomemtics) Flashcards
Enumerate types of parasympathomimetics
Choline esters:
* Acetylcholine
* Methacholine
* Carbachol
* Bethanechol
Cholinomimetic Alkolids:
* Pilocarpine
Anti-choline esterase:
* Reversible —> Physostigmine & Neostigmine
* Irreverible —> organophsphorus compounds
Absorption & distribution of Acetylcholine
- Not absorbed orally (by GIT)
- Doesn’t pass BBB (not affect CNS)
Receptors affected by Acetylcholine
- At small dose –> muscarinic Only
- At large dose —> Muscarinic & Nicotinic
Muscarinic effect of Acetylcholine can be blocked by ____
Atropine
Nicotinic effect of Acetylcholine can be blocked by:
- Nn: G blocker
- Nm: Curare
general effect of atropine on parasympathomimetics
opposing –> can reverse action of parasympathomimetics
Clinical uses of acetylcholine
Not used clinically
very rapidly destroyed by Choline estrases
receptors effect by Methacholine
Muscarinic only
Clincal uses of methacholine
Diagnosis of bronchial hyper-reactivity
NOT TREAT
Receptors affected by Carbachol
both nicotinic & Muscarinic
receptors affected by Bethanechol
Muscarinic only
Choline esters not destroyed by Choline esterases
Carbachol & Bethanechol
Choline esters acting on Muscarinic receptors only
- Methacholine
- Bethanechol
Metha w Betha
Uses of Carbachol & bethanechol
- used for post-op urine retention
- used for paralytic ileus
- used for to prevent stomach dilution
- CARBACHOL —> used in glaucoma
Absorption & Distribution of pilocarpine (cholinomimetic alkaloid)
- well absorbed from GIT
- Crosses BBB (so avoided in Parkinsonism)
