Lecture V Flashcards
M1 Receptor
Activates Myenteric Plexus
M2 Receptor
Decreases Heart rate and contraction
M3 Receptor
- Contracts circular ciliary muscle (Pupillary constriction)
- Contracts bronchiolar muscle
- Contracts GI smooth muslce
- Contracts bladder detrusor muscle
Stimulates GI secretions, eccrine sweat glands, tear glands, salivary glands
M3 dry your patient up
Nn Receptor
On the membrane of post ganglionic cells of both sympathetic and parasympathetic
Nm Receptor
On the membranes of skeletal muscles.
Nicotine
Nicotinic Receptor Agonist
- Selective for Nn receptor
- Limited to preparations for smoking cessation
Succinylcholine
Blocks Nm receptor
*Muscle relaxant during intubation.
Method of Action: Prolonged depolarization of the membrane. Sits ont eh membrane and keeps it depolarized.
Acetylcholine
- Binds to Nicotinic and Muscarinic receptors
- Rapidly hydrolyzed by acetyl- and plasma cholinesterases
No therapeutic use
Methacholine
Muscarinic effects (on smooth muscle and heart)
- Longer duration of action than acetylcholine.
- Hydrolyzed more slowly by acetylcholinesterases
- Used to diagnose bronchail hyperactivity in patients with asthma
- Toxicity: Bronchiolar constriction
- Contraindication: Patients on beta blockers
Carbachol
Muscarinic and nicotinic receptors
- Miotic agent in ophthamology (constriction) to reduce intra occular pressure in GLAUCOMA
Bethanechol
Muscarinic selectivity
*Less CV Effects (little M2 activity)
Uses: Urinary retention
Toxicity: Bradycardia, bronchoconstriction
Contraindications: asthma bradycardia
Muscarine
Highly selective for muscarinic
Toxic
Pilocarpine
Muscarinic only
*Crosses the BBB
Uses: Problems of dry mouth, glaucoma
*Hypotension, Slowed AV conduction, excessive salivation
Neostigmine
Poor penetration of BBB (Nm receptors)
Uses: Myasthenia gravis, reversal of non-depolarizing neuromuscular blockade
Toxicity: Excess
Contraindication: Intestinal obstruction (promotes gut motility)
Edrophonium
Nm receptor activation
*Rapid onset, short duration
Uses: myasthenia gravis (too much or too little Ach inhibitor. Inhibits the cholinesterases so if the patient gets a little bit better it is due to the disease progression, if it gets worse, it is disease progression
Toxicity: Bradycardia
Contraindications: intestinal block
Physostigmine
CROSSES BBB (inactivated by plasma cholinesterases)
Uses: Delerium with excess anticholinergic activation (prevents the degradation of Ach).
Donepezil
Reversible inhibitor of Acetylcholinesterases in the CNS
Used in alzheimers disease
Organophosphates
Irreversible Cholinesterase inhibitors
Found in Insecticides and nerve gases
DUMBBELS
Diarrhea, Urination, Miosis, Bradychardia, Bronchorrhea, Emesis, Lacrimation, Salivation
Treatment of severe organophosphate poisoning
1- Mechanical Ventilation
2- Suction of oral secretions
3- Atropine to protect from systemic muscarinic activation
4- Reactivation of the alkylphosphorylate acetylcholinesterase with 2-PAM.
Echothiophate
Organophospate used to produce long term miosis in the treatment of open angle glaucoma
Atropine
Muscarinic antagonist
Uses: relieve urgency and frequency of micturition, relieve hypermotility of colon and hypertonicity of small intestine, treatment of organophosphate poisoning, induce mydriasis, reverse bradycardia
Scopolamine
Muscarinic antagonist
Uses: Preparation in surgical anesthesia to minimize secretions.
Treat nausea and vomiting associated with motion sickness and in chemotherapy
Glycopyrrolate
Muscarinic antagonist
Uses: Prevent overstimulation of the gut during reversal of neuromuscular block
Atropine Poisoning
Blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone.
