Cholinergic Agonists Flashcards by Tesla Trooper

Why does Ach lacks therapeutic action?

Multiplicity of actions (leading to diffuse effects)

Rapid inactivation by the cholinesterases

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What are the effects of Ach on heart rate and cardiac output?

Low heart rate
Low cardiac output
{Due to reduction in the rate of firing at the sinoatrial (SA) node}

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Injection of ACh causes vasodilation and lowering of blood pressure by activating ____ receptor on the endothelium.

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How does NO produces vasodilation?

M3 receptor stimulated → Arginine to NO → protein kinase G in SMCs → hyperpolarization and SMCs relax (PDE inhibition)

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______________, a direct-acting cholinergic agonist, is used to assist in the diagnosis of asthma due to its
bronchoconstricting properties

Methacholine

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In the genitourinary tract, ACh __________ (increases/decreases) the tone of the detrusor muscle, causing urination

increases

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In GI tract, it __________ (enhances/inhibits) secretions and motility

enchances

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In the eye, ACh is involved in stimulation of ciliary muscle contraction for _______ (far/near) vision and in the constriction of the pupillae sphincter muscle, causing _________ (miosis/mydriasis)

near

miosis

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ACh (1% solution) is instilled into the __________ (anterior/posterior) chamber of the eye to produce miosis during ophthalmic surgery

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_____________ lacks nicotinic actions (due to addition of the methyl group), but does have strong muscarinic activity

Bethanechol

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__________ has about a 1-hour duration of action

bethanechol

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bethanechol is used to _________ (stimulate/inhibit) the atonic bladder

stimulate

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____________ is used for postpartum or

postoperative, nonobstructive urinary retention

bethanechol

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Adverse effects of cholinergic agonists?

Nausea
Diarrhea
Bronchospasm
Urinary urgency
Miosis

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Carbachol’s intraocular use provides miosis for eye surgery and _________ (increase/decrease) intraocular pressure in the treatment of glaucoma

decrease

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Which one is more potent?

Carbachol OR Pilocarpine

carbachol

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___________ can penetrate into CNS (carbachol/bethanechol/pilocarpine)

pilocarpine

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The drug of choice for EMERGENCY lowering of intraocular pressure of both open-angle and angle-closure glaucoma is _____________ (pilocarpine/carbachol)

pilocarpine

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How does pilocarpine lowers IOP?

Pilocarpine is extremely effective in opening the trabecular meshwork around the Schlemm canal, causing an immediate drop in intraocular pressure because of the increased drainage of
aqueous humor.

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Onset of action and duration of action for pilocarpine

Onset = few minutes
Duration = 4 to 8 hours

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What r agents other than pilocarpine that can be used to treat glaucoma?

Dorzolamide and Timolol, are effective in treating glaucoma but are not used for emergency lowering of intraocular pressure
Carbachol

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__________ is beneficial in promoting salivation in patients with xerostomia resulting from irradiation of the head and neck

pilocarpine

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___________, which is characterized by dry mouth and lack of tears, is treated with oral pilocarpine tablets and cevimeline

Sjögren syndrome

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___________ can cause blurred vision, night blindness, and brow ache

pilocarpine

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Poisoning with __________ is characterized by | exaggeration of various parasympathetic effects which can be counteracted by parenteral atropine

pilocarpine

The effects of pilocarpine are similar to those produced by consumption of mushrooms of the genus ________

Inocybe

Summarise the cholinergic agonists 1. Ach 2. Bethanechol 3. Carbachol 4. Pilocarpine

1. Ach for miosis in ophthalamic surgery 2. Bethanechol for tx of urinary retention 3. Carbachol for miosis and lowering IOP for glaucoma 4. Pilocarpine for emergency tx of glaucoma

Excess of edrophonium can cause ___________

cholinergic crisis

What is edrophonium

Reversible cholinesterase inhibitor

Edrophonium is used for the diagnosis of ________________

myasthenia gravis

IV injection of edrophonium rapidly ___________ (increases/decreases) the strength of the muscle which confirms the dx of myasthenia gravis

increases

Edrophonium also ___________ (reverse/enhance) neuromuscular blocking effects of drugs

reverse

Edrophonium is a ________ (short/intermediate) acting drug

short (10-20min)

Physostigmine and neostigmine are __________ (short/intermediate) acting drugs

intermediate

_____________ is contraindicated in intestinal and urinary nonobstructive retention

neostigmine

WHich one of the following enters CNS? | Physostigmine or neostigmine

physostigmine (so it produces paralysis of skeletal muscles if given in high doses)

Adverse effects of physostigmine

Convulsions and skeletal muscle paralysis

___________ is used for the chronic management of myasthenia gravis

pyridostigmine

duration of action of pyridostigmine is _________

3-6 hrs

tacrine is not used for tx of AD bcz of ____________

hepatotoxicity

Donepezil, rivastigmine, and galantamine all are used to delay progression only but can't stop ___________________

Alzheimers disease

_________ is used for postoperative abdominal distention and for gastric atony following bilateral vagotomy

Bethanechol

parenteral (IV or IM) administration of ___________ (carbachol/bethanechol) may cause cardiac arrest

bethanechol

Patients with no clinically apparent asthma are ______ (more/less) sensitive to methacholine-induced bronchoconstriction than normal patients

When used before surgery to treat acute narrow-angle glaucoma, pilocarpine is often given in combination with an indirectly acting muscarinic agonist such as ______________

physostigmine

What r the contraindications of direct acting cholinergic agonists?

``` Peptic ulcer Asthma Cardiac disease Parkinson disease Hyperthyroidism Mechanical obstruction of the GI or urinary tract ```

Nicotine-based products and varenicline (Chantix), direct-acting nicotinic receptor agonists, are approved for use in _________ cessation

smoking cessation

_________ acts as an antidote for organophosphorus insecticide and nerve gas poisoning

Pralidoxime

Postoperative ileus and congenital megacolon, and urinary tract retention can be treated with direct or indirectly acting cholinomimetic drugs such as ___________ and _____________

bethanechol | neostigmine

____________ are also used to increase the tone of the lower esophageal sphincter

Bethanechol and neostigmine

Myasthenia gravis is an autoimmune disease in which antibodies complex with ____________ receptors at the neuromuscular junction to cause skeletal muscle weakness and fatigue

nicotinic

Adverse effects of cholinergic agonists | Mnemonic - DUMBBELS

``` Diarrhea Urination Miosis Bradycardia Bronchorrhea Emesis Lacrimation Salivation ```

Myasthenia gravis can be diagnosed using the __________ test, which can also assess the adequacy of treatment with AChE inhibitors

Tensilon

In tensilon test, if there is no effect, or | if muscle weakness increases, the dose of the AChE inhibitor is too ________ (high/low)

high

____________ can be used following surgery to reverse neuromuscular blockade and paralysis resulting from adjunct use of nondepolarizing agents

Neostigmine or edrophonium

Atropine and scopolamine poisoning that results in severe body temperature elevation or tachycardia can be treated with ____________(physostigmine/neostigmine), which reverses the central and the peripheral effects of competitive muscarinic antagonists

physostigmine

Many lipid-soluble ____________ are used as insecticides or nerve gases and may be absorbed in sufficient quantities from the skin or lungs to cause cholinergic intoxication

organophosphates

Examples of agents that cause cholinergic intoxication 1. insecticides 2. nerve gas

insecticide = malathion | nerve gas = sarin gas

What is the treatment of cholinergic intoxication?

(1) Maintain respiration and decontaminate to prevent further absorption. (2) Administer atropine parenterally to inhibit muscarinic effects. (3) Administer pralidoxime within minutes of exposure.

Choline uptake is inhibited by _____________

hemicholinium

____________ interacts with synaptobrevin and other proteins to prevent ACh release

Botulinum toxin

__________ is used for tx of blepharospasm, strabismus/hyperhidrosis, dystonia, and cosmetics

Botulinum

What are the uses of edrophonium?

Dx of MG | Antidote for competetive NM blockers

What r the uses of neostigmine?

tx of MG tx of postoperative abd distention and urinary retention antidote for competetive NM blockers

What are the uses of physostigmine?

Reverses CNS effects of atropine Reverses CNS and CVS effects of TCA Increases bladder and intestinal motility

Echothiophate is used in the tx of ___________ glaucoma

open angle

Cholinergic Agonists Flashcards

(66 cards)