Direct Cholinomimetics and indirect cholinomimetics Flashcards by Hadley C

What are direct cholinomimetics

Agonists at muscarinic cholinoreceptors and increase parasympathetic activity

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Direct cholinomimetics work at muscarinic cholinoreceptors and thus have similar effects as stimulation of the ___ division

Parasympathetic

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Examples of direct cholinomimetics

Bethanechol
Methacholine
Pilocarpine
Carbachol

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What is bethanechol

Direct cholinomimetic agent used to induce bladder and GI smooth muscle contraction (motility)

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What is bethanechol structurally similar to

Acetylcholine

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How does bethanechol prevent urine retention and ileus

Stimulating smooth muscle motor activity

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What is methacholine

Direct cholinomimetic , parasympathomimetic drug, used in the bronchial challenge test to help diagnose asthma

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How is methacholine used for diagnosis of asthma with bronchial hypersensitivity

If asthma is less clinically apparent they are more sensitive to methacholine challenge, compared to normal patients

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What is pilocarpine

Potent stimulator of sweat, tears, and saliva used for both open and closed angle glaucoma

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What does pilocarpine do

Contractsciliary muscles of the eye (treat open angled glaucoma) and causes pupillary sphincter contraction (closed angle glaucoma).

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How is pilocarpine administered

Ocular insert or as eyedrops

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MOA of pilocarpine

Contract the ciliary muscle of the eye for open angle glaucoma and the pupillary sphincter for closed angle glaucoma.

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What is pilocarpine resistant to

Acetylcholinesterase

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Patients show __ after administration of pilocarpine

Miosis

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What is carbachol

Cholinomimetic agent similar to ach

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What is carbachol used for

Open angle glaucoma

Rare-closed angle glaucoma

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How does carbachol help with open angle glaucoma

Helps relieve intraocular pressure and can be used to cause pupillary constriction

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What is an indirect cholinomimetic

Decrease the action of the acetylcholinesterase enzyme (which works to break down acetylcholine)

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What are indirect cholinomimetics also called

Anticholinesterases

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What does indirect cholinomimetics lead to

Increased duration and action of the neurotransmitter acetylcholine

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What indirect cholinomimetics don’t cross the BBB

Edrophonium, neostigmine and pyridostigmine

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What are indirect cholinomimetics that that don’t cross the BBB used to treat

Myasthenia gravis

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What is neostigmine used to treat

Ileus

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What are the indirect cholinomimetics examples

Physostigmine
Donepezil
Ambenonium
Neostigmine
Pyridosstigmine
Edrophonium
Echothiophate
Tacrine
Rivastigmine
Galantamine

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Indirect cholinomimetics that cross the BBB care __ acting

Centrally

What is physostigmine used for

Atropine overdose and dementia

What is donepezil used for

Alzheimer’s

Describe endrophonium

Reversible acetylcholinesterase inhibitor, which prevents the breakdown of acetylcholine

How does edrophonium work

Competitively inhibiting acetylcholinesterase at the neuromuscular junction

Edrophonium is used to diagnose __ __

Myasthenia gravis

Describe the tensilon test

Myasthenia gravis can be diagnosed with edrophonium as patients immediately show decreased muscle weakness

What are pyridostigmine and neostigmine

Cholinomimetics or parasympathomimetics, which work to reversible inhibit acetylcholinesterase and do not cross the BBB

What do we use pyridostigmine and neostigmine treat

Myasthenia gravis

Neostigmine in addition to treating myasthenia gravis, treats what

Reverse neuromuscular blocking agents in anesthesia

Why are pyridostigmine and neostigmine used for long term treatment of myasthenia gravis

Improve muscle function by slowing the natural enzyme cholinesterase that degrades acetylcholine in the motor end plate; the neurotransmitter is therefore around longer to stimulate its receptor

What else can neostigmine used to also treat

Post operative and neurogenic ileus as well as in treating urinary retention

Physostigmine

More hydrophobic than other indirect cholinomimetics, and crosses the BBB

What is physostigmine used to treat

Atropine and anticholinergic drug overdoses

Physostigmine is helpful in inducing ___

Miosis | Leading to decreased intraocular pressure

What is donepezil

Acetylcholinesterase inhibitor which is used for treating Alzheimer’s disease

In Alzheimer’s ,patients have decreased ___ levels

Acetylcholine

How does donepezil treat Alzheimer’s

Centrally acting acetylcholinesterase inhibitors help increase the available amount of relative acetylcholine

What is pilocarpine (pilocar)

Direct cholinergic agonist that contracts the iris sphincter and ciliary muscle of the eyes

What indicates pilocarpine

Glaucoma and xerostomia (dry mouth)

Side effects of pilocarpine

Retinal detachment, decreased visual acuity and eye. Irritation, cholinergic side effects (bradycardia, bronchospasm, hypotension, and diarrhea)

Who should we not give pilocarpine to

Asthma and bradycardia | Because causes systemic effects

Pilocarpine is a direct acting cholinergic agonist that ___ aqueous blood flow

Increases

Pilocarpine mimics the effects of ____ and serves as a messenger between nerve cells and various organs throughout the body

Acetylcholine

What does pilocarpine , a parasympathomimetic agent stimulate

Cholinergic receptors and may lead to systemic effects such as bronchospasm or hypotension

Pilocarpine treacle intraocular pressure in patients with angle closure glaucoma. How

Contracts the iris sphincter of the eyes and causes pupil constriction or miosis

Pilocarpine contracts the ciliary muscle and focuses the lens for __ vision

Near

Indications for pilocarpine

Xerostomia | Glaucoma

How does pilocarpine treat xerostomia

Stimulates salivaryglands

What causes xerostomia

Meds, chemotherapy, or Sjögren’s syndrome

How does pilocarpine treat glaucoma (open angle)

Lowers IOP Second line for open angle glaucoma Contract ciliary muscles and widens to facilitate aqueous humor outflow

How does pilocarpine treat patients with glaucoma (closed angle)

Contraction of the iris sphincter pulls the iris from impeding aqueous humor outflow Can treat acute cases of primary closed angle glaucoma

Side effects of pilocarpine

Detached retina Decreased visual acuity Eye irritation Cholinergic effects

Why does pilocarpine cause detracted retina

Lens and vitreous to move forward and may create a retinal tear. Sustained contraction of the ciliary muscle may lead to retinal detachment

How does pilocarpine cause decreased visual acuity

Constricting pupils, may cause blurred vision and decreased visual acuity. Contraction of the ciliary muscle focuses the lens for near vision.

Why does pilocarpine cause eye irritation

Administered topically to the lower conjunctiva as a solution or gel.

What are the cholinergic effects of pilocarpine

Bradycardia, bronchospasm, hypotension, and hypersalivation , urinary urgency, diarrhea, and sweating.

What can be administered to reverse systemic toxicity caused by pilocarpine

Atropine

Who should you not give pilocarpine to

Asthma or bradycardia | Don’t want to worsen symptoms

Acetylcholinerase inhibitor poisoning /organophosphate toxicity/cholinergic overdose. Who is it seen in

Farmers , as organophosphate are commonly found in insecticides

What happens in acetylcholinesterase inhibitor poisoning

Irreversibly inhibit acetylcholinesterase

Antidotes to acetylcholinesterase inhibitor poisoning

Atropine and pralidoxime

Symptoms of acetylcholinesterase inhibitors

DUMBBELSS | Including excitation

Why get DUMBBELSS symptoms with acetylcholinesterase inhibitor poisoning

Massive discharge of the parasympathetic nervous system

Why get excitation with acetylcholinesterase inhibitor poisoning

CNS effects of cholinergic overdoes bc excitation of both CNS and muscle

What are acetylcholinesterase inhibitors

Drugs that inhibit the enzyme which breaks down acetylcholine

Antidotes to acetylcholinesterase inhibitor

Atropine and pralidoxime

How does atropine stop acetylcholinesterase inhibitor

Competitive antagonist of muscarinic acetylcholine receptors, which is why it is a great antidote

Why does pralidoxime antidote to acetylcholinesterase inhibitor

For organophosphate poisoning in conjunction with atropine Binds to the site where an acetylcholinesterase inhibitor has attached, then regenerates the enzyme to allow it to function again and break down more acetylcholine at the synapse