Pharmacology Exam 3

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Acetylcholine site of action
- cholinergic agonist
- muscarinic receptors
- nicotinic receptors
Properties of Acetylcholine
- rapidly hydrolized
- for surgical use only to constrict iris
Physiological effect of ACH at lower doses
- muscarinic action
- Blood pressure
Physiological effect of acetylcholine at higher doses
- ganglionic
- primarily nicotinic
- parasympathetic effects
Respiratory effects of acetylcholine
- bronchoconstricion
- increased mucous
GI effects of acetylcholine

digestion and motility
Methacholine
- ACH-CH₃
- cholinergic agonist
- muscarinic specific
- little nicotinic effect
uses of methacholine
- diagnosis of asthma
- use a B₂ agonist to overcome the effect
Bethanechol
- cholinergic agonist
- little nicotinic effect
- highly resistant to AChE and Pseudocholinesterase
- used for systemic effects
Uses of Bethanechol
- urinary retention
- abdominal distention
- gastric atony (no movement)
Avoid used of bethanechol with
- GI obstruction
- leads to ischemia and tissue necrosis
Adverse reactions that occur with muscarinic cholinergic agonists
- salivation
- nausea
- GI cramping
- warm, sweating
- faintness
Nicotine
- cholinergic agonist
- activates neuromuscular junction
- leads to depolarization block (overstimulation)
- activates chemoreceptors
- stimulates respiration
Carbachol
- cholinergic agonist
- little hydrolysis at AChE and PSChE
- high nicotinic effect
- some muscarinic effect (GI/Bladder)
Use for carbachol
- glaucoma
- causes miosis
- enhances aqueous humor outflow (muscarinic)
muscarine
- cholinergic agonist
- mushrooms
- hypotention
- decreased HR
- increased gland secretions
Pilocarpine & Cevimeline
- cholinergic agonist
- tertiary amines that cross BBB
Pilocarpine use
- glaucoma treatment
- xerostomia
side effects of pilocarpine and cevimeline

sweating
cevelemine
- cholinergic agonist
- m1 and m3 selective
- fewer side effects
- less toxicity
Reversible AChE inhibitors
- cations
- competitively bind to the anionic site of AChE
Edrophonium
- reversible AChE inhibitor
- quaternary alcohol (cannot cross BBB)
- differential diagnosis of myasthenia gravis
Physostigmine
- reversible AChE inhibitor
- freely crosses BBB
- glaucoma
- myasthenia gravis
- reverse mydriasis or NMJ blockade
Neostigmine
- reversible AChE inhibitor
- quaternary amine (can't cross BBB)
- nicotinic agonist (NMJ)
- reversible AChE inhibitor
Neostigmine uses
- myasthenia gravis
- glaucoma
- NMJ blockade reversal (curariform toxicity)
- GI and Urinary atony
- Antimuscarinic drug overdose (Atropine)
Donepezil & Rivastigmine
- treat alzheimer's disease
- reversable AchE inhibitors
Direct acting cholinergic agonists
- acetylcholine
- Metacholine
- Bethanechol
- Muscarine
- Pilocarpine
- Cevimeline
- Nicotine
- Carbachol
Reversible AChE inhibitors
- Edrophonium
- Physostigmine
- Neostigmine
- Donepezil
- Rivastigmine
Irreversible AChE inhibitors
- Organophosphates
- covalently bind to the esteratic side of AChE
- insecticide
- sarin gas
Use of irreversible AChE inhibitors leads to:

overstimulation of parasympathetics leading to paralysis of respiratory muscles
Treatments for exposure to irreversible AChE inhibitors
- vital sign maintenance
- atropine
- pralidoxime
- bzd's
Toxicology of AChE Inhibitors 1st symptoms
- Muscarinic effects
- miosis
- tightness of chest
- salivation/sweating
- bradycardia
Toxicology of AChE inhibitors 2nd effect
- Nicotinic effects
- skeletal muscle fasciculations
- weakness
- paralysis
Toxicology of AChE inhibitors (3rd phase)
- CNS
- restless/anxiety
- confusion
- convulsion
4th toxicological effect of AChE inhibitors
- respiratory arrest
- paralysis of muscles
- central depression of respiration
- airway obstruction (increased secretions)
Used for Glaucoma
- pilocarpine
- physostigmine
used for paralytic ileus and bladder atony
- bethanechol
- neostigmine
used for xerostomia
- pilocarpine
- cevimeline
used for myasthenia gravis
- edrophonium (diagnosis and dose check)
- neostigmine
antidote for atropine poisoning or TCA overdose

physostigmine
Used for alzheimer's/dementia
- donepezil
- rivastigmine
- galantamine
other uses for cholinergic agonsits
- paroxysmal supraventricular tachycardia
- edrophonium for specific arrhythmias
Toxicity of direct actin muscarinic stimulants
- N/V
- Diarrhea
- Urination/Salivation/Sweating
- cutaneous vasodilation
- bronchial constriction
Acute toxicity of direct acting nicotinic stimulants
- central stimulant
- depolarization blockade => respiratory paralysis
- HTN and arrhythmias
Chronic toxicity of direct acting nicotinic stimulants
- vascular disease risk
- sudden coronary death
- ulcer recurrences
- varenicline (partial agonist)
Major pharmacologic effects of muscarinic receptors
- SLUDGE
- Salivation
- Lacrimation
- Urination
- Defication
- GI motility
- Emesis
Myasthenia gravis
- autoantibodies against alpha 1 subunit of the nicotinic receptor
- results in weakness of commonly used voluntary muscles
Makes Myasthenia gravis worse
- activity
- aminoglycosides
Myasthenia gravis vs. cholinergic crisis
- myasthenia needs more AChE inhibition
- Crisis needs less AChE inhibition
- edrophonium used to distinguish

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Rx2013

44039

Card Set

Pharmacology Exam 3

Description

Cholinergic Agonists

Updated

2010-10-21T19:57:13Z

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