cholinergic drugs (agonists and antagonists) Flashcards
Cholinomimetics agents are divided to
- direct agents
2. indirect agonists (anticholinesterases)
direct cholinominetics agents - drugs
- Bethanechol
- Carbachol
- Metacholine
- Pilocarpine
Bethanechol - clinical use
- Postoperative ileus
- neurogenic ileus
- urinary retention
Bethanechol - action
cholinomimetic agents (direct agonist) –> activates bowel and bladder smooth muscle (reistant to AChE)
Carbahol - clinical use
constricts pupil and relieves intraocular pressure in open-angle glaucoma
Carbahol - mechanism of action
cholinomimetic agents (direct agonist)
Metacholine - clinical use
challange test for diagnosis of asthma
Metacholine - mechanism of action
cholinomimetic agents (direct agonist) –> stimulates M receptors in airway when inhaled (M3)
pilocarpine - clinical use
- Potent stimulator of sweat tears, and saliva - xerostomia (Sjogren syndrome)
- open angle and closed angle glaucoma (1st line in acute)
pilocarpine - mechanism of action
cholinomimetic agents (direct agonist) --> contracts ciliary muscle of eye (open-angle glaucoma), pupillary sphincter Resistant to AChE)
direct cholinominetics agents - drugs and which is AChE resistant
- Bethanechol –> resistant
- Carbachol
- Metacholine
- Pilocarpine –> resistant
Indirect antagonists (anticholinesterases) - drugs
- Donepezil
- galantamine
- rivastigmine
- Edrophonium
- Neostigimine
- Physostigmine
- Pyridostigmine
- tacrine
anticholinesterases used in Alzheimer
- Donepezil
- galantamine
- rivastigmine
- tacrine
Edrophonium - clinical use
historically, diagnosis of myasthenia gravis (extremely short acting)
diagnosis of myasthenia gravis
- historically: Edrophonium –> extremely short acting
2. NOW: anti AChR Ab test
Neostigmine - BBB
No BBB (quaternary amine)
Neostigmine - clinical use
- postoperative and neurogenic ileus
- urinary retention
- Myasthenia gravis
4 . Reversal of NMJ blockade (postoperative)
Physostigmine - clinical use
- anticholinergic toxicity
Physostigmine - BBB
crosses BBB (tertiary amine)
Pyridostigmine - BBB
No BBB (quaternary amine)
Pyridostigmine - clinical use
- Myasthenia Gravis (long acting)
with cholinomimetics agents using, be careful with
exacerbation of 1. asthma and 2. COPD
3. peptic ulcers
(when giving to susceptible patients)
Cholinesterase inhibitor poisoning is often due to
organophosphates, such as parathion, that IRREVERSIBLY inhibit AChE
organophosphates are often components of …
insecticides
organophosphates poisoning is often seen in
farmers
direct vs inderct cholinomimetics agents toxicity
similar, but because indirect influence the nicotinic as the muscarinic actions, more nicotinic manifestations may be observed
cholinommetics agents - adverse effects
DUMBBELLSS (M:muscarinic, N: nicotinic) Diarrhea (M) Urination (M) Miosis (M) Bronchospasm (M) Bradycardia (M) Excitation of skeletal muscle and CNS (N) Lacrimation (M) Sweating (M) Salivation (M)
organophosphates poisoning - antidote (and mechanism of action
atropine (competitive inhibitor) + pralidoxime (regenerates AChE if give early, NOT in BBB)
cholinomimetic agents - drugs (all)
Direct: 1. Bethanechol 2. Carbachol 3. Metacholine
4. Pilocarpine
Indirect: 1. Donepezil 2. galantamine 3. rivastigmine
4. Edrophonium 5. Neostigimine 6. Physostigmine
7. Pyridostigmine 8. tacrine
Muscarinic antagonists - drugs
- Atropine
- Homatropine
- tropicamide
- Benzotropine
- Glycopyrrolate
- Hyoscyamine
- dicyclomine
- ipratropium
- tiotropium
- Oxybutunin
- solifenaxin
- tolterodine
- Scopolamine
Muscarinic antagonists - drugs of the eye
- atropine
- homotropine
- tropicamide
Muscarinic antagonists - drugs of the CNS
- benzotropine
2. scopolamine
Muscarinic antagonists - drugs of GI/respiratory
glycopyrrolate
Muscarinic antagonists - drugs of GI
- hyoscyamine
2. dicyclomine
Muscarinic antagonists - drugs of GU
- oxybutynin
- solifenacin
- tolterodine
Muscarinic antagonists - drugs of eye and clinical use
- atropine 2. homotropine 3. tropicamide
produce mydriasis and cycloplegia
Muscarinic antagonists - drugs of the CNS
- benzotropine –> parkinson, acute dystonia
2. scopolamine –> motion sickness
Muscarinic antagonists - drugs of GI/respiratory and mechanism of action
glycopyrrolate :
oral: drooling, peptic ulcer
parental: preoperative use to reduce airway secretions
Muscarinic antagonists - drugs of GI and clinical use
- hyoscyamine 2. dicyclomine
antispasmodics for irrtavle bowel syndrome
Muscarinic antagonists - drugs of Respiratory and clinical use
- Ipratropium 2. tiotropium
- -> COPD, ASTHMA
Muscarinic antagonists - drugs of GU and mechanism of action
- oxybutynin 2. solifenacin 3. tolterodine
reduce bladder spasms and urge urinary incontinence (overactive bladder)
Atropine - clinical use
- bradycardia
2. opthalmic applications (produce mydriasis and cycloplegia)
action of atropin in different organ systems
eye –> produce mydriasis and cycloplegia
airway –> decreases secretion
stomach –> decreases acid secretion
gut –> decreases motility
bladder –> decreases urgency in cystitis
general action of Atropine
blocks DUMMBBeLSS of cholinesterase inhibitor poisoning
does not block skeletal muscles and CNS because are nicotinic receptor mediated
Aropine - adverse effects
- increased body Q (decreased sweating)
- rapid pulse
- dry mount
- dry, flushed skin
- cycloplegia
- constipation
- disorientation
- acute agle-closure glaucoma in elederly (mydriasis)
- urinary retention in men with BOH
- hypertermia in infants
plant with atropine
Jimson weed (Datura) –> gardner’s pupil (mydriasis due to plant alkaloids