Cholinergic Agonists and Antagonists Flashcards by Billy Harrah

In most organs, which mAChR receptor predominants?

Which predominates in the heart?

Which in smooth muscle?

1) M3
2) M2
3) M3, M2

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What are the parasympathetic effects on the iris sphincter muscle?

On the ciliary muscles?

1) Contraction (miosis)

2) Contraction for near vision

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What are the parasympathetic effects on the SA node?

What are the parasympathetic effects on the atria?

What are the parasympathetic effects on the AV node?

What are the parasympathetic effects on the ventricles?

1) Decrease HR
2) Decrease in contractile strength and refractory period
3) Decrease in conduction velocity and increase refractory period
4) Decrease in contractile strength

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What are the parasympathetic effects on the arteries and veins?

Via what?

Dilation via EDRF

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What are the parasympathetic effects on the bronchial muscles?

What are the parasympathetic effects on the bronchial glands?

1) Contraction

2) Stimulation

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What are the parasympathetic effects on GI motility?

What are the parasympathetic effects on GI sphincters?

What are the parasympathetic effects on GI secretion?

1) Increase
2) Relax
3) Stimulate

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What are the parasympathetic effects on the detrusor muscle?

What are the parasympathetic effects on the Trigone and sphincter?

1) Contraction

2) Relax

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What are the parasympathetic effects on the sweat, salivary, lacrimal and nasopharyngeal glands?

Secretion of glands

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Accommodative esotropia is a misalignment of the eyes that can be diagnosed and treated with?

Cholinomimetic agonists

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What is the most widely used choline ester for GI/GU disorders, including postoperative ileus, congenital megacolon, urinary retention, and esophageal reflux?

What must the physician be certain of otherwise the drug may exacerbate the problem and may even cause perforation?

1) Bethanechol

2) No obstruction

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Pilocarpine and cevimeline are used to do what?

What condition does it help?

1) Increase salivary secretion

2) Dry mouth from Sjögren’s syndrome

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The overdose of what drug causes predictable muscarinic effects such as nausea, vomiting, diarrhea, urinary urgency, salivation, sweating, cutaneous vasodilation, and bronchial constriction?

What antimuscarinic compounds do you use to treat this?

1) Pilocarpine and the choline esters

2) Atropine

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Mushrooms of the genus Inocybe can cause?

Muscarinic poisoning

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What are the major contraindications to the use of mAChR agonists that are distributed systemically?

1) Asthma
2) Hyperthyroidism
3) Coronary insufficiency
4) Acid-peptic disease

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CNS stimulation (convulsions progressing to coma), Skeletal muscle end plate depolarization, Respiratory paralysis, Hypertension, and Cardiac arrhythmias are all acute toxicity effects of?

Nicotinic stimulants

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What are the treatments for acute toxicity effects of nicotinic stimulants?

1) Atropine ganglia

2) Parenteral anticonvulsants (diazepam)

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What is approved for intraocular use during surgery and causes miosis (reduction in pupil size)?

Acetylcholine

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What is administered by inhalation for the diagnosis of bronchial airway hyperreactivity in patients who do not have clinically apparent asthma?

Methacholine

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What can be used to treat patients with urinary retention and heartburn?

What type of agonist is it?

1) Bethanechol

2) Selective mAChR agonist

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What is a nonspecific cholinergic agonist that is used for the treatment of glaucoma or to produce miosis during surgery or ophthalmic examination?

Carbachol

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What is given as an oral tablet used to treat dry mouth (xerostomia) in patients with Sjögren’s syndrome?

It is metabolized via what?

1) Cevimeline

2) P450 pathways

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What is approved for xerostomia treatment in patients with Sjögren’s syndrome or head and neck cancer treatment related xerostomia (PO), miosis during ophthalmic procedures (topical), and for glaucoma (topical)?

What type of agonist is it?

1) Pilocarpine

2) mAChR agonist

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Bethanechol may produce urinary tract infection if?

Sphincter fails to relax

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What is FDA approved for smoking cessation?

Varenicline

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Varenicline is a partial agonist that binds with high affinity and selectivity to what receptor located in the brain to stimulate receptor-mediated activity?

α4β2 nicotinic acetylcholine receptors

Varenicline causes a sustained release of what NT to reduce craving and withdrawal symptoms associated with smoking cessation?

Dopamine

What is the most common adverse effect of Varenicline? What are some serious adverse effects?

1) Nausea 2) Changes in behavior, agitation, depressed mood, and suicide

Acetylcholinesterase (AChE) inhibitors such as Alcohols and Carbamic acid esters have what type of charge? What type of binding does it have to AChE? Which is more longer lasting?

1) Positive or neutral charge 2) Noncovalent and reversible 3) Carbamic acid esters

What makes AChE inhibitors such as Organophosphates toxic to the CNS? What type of binding does it have to AChE?

1) Neutral charge and highly lipid-soluble | 2) Covalent and irreversible

What category of AChE inhibitors such as neostigmine, pyridostigmine, edrophonium, echothiophate, ambenonium are poorly absorbed? What category of AChE inhibitors such as physostigmine, donepezil, tacrine, rivastigmine, galantamine are well-absorbed?

1) Quaternary and charged AChE inhibitor | 2) Tertiary and uncharged AChE inhibitors

What is required in order to reestablish the termination of ACh signaling at the neuromuscular junction?

Regeneration of AChE

What is the mechanism of action for AChE inhibitors?

ACh accumulation throughout the body and activation of nAChRs and mAChRs

What do AChE inhibitors stimulate at autonomic effector organs? What do AChE inhibitors stimulate at, followed by depression or paralysis, all autonomic ganglia and skeletal muscle? What do AChE inhibitors stimulate, with occasional subsequent depression, in the CNS?

1) mAChRs 2) nAChRs 3) Cholinergic receptor sites

The eye, respiratory tract, GI tract, and urinary tract are innervated by what receptors?

mAChRs

What does moderate doses of AChE inhibitors do to HR? How does it affect CO? How does it affect atrial and ventricular contractility? How does it affect BP?

1) Bradycardia 2) Decreased cardiac output 3) Decreased atrial and ventricular contractility 4) Increase in blood pressure

Some quaternary carbamate AChE inhibitors such as neostigmine have what additional effects at the NMJ?

Direct nicotinic agonist effects

What effect does AChE inhibitors have on paralysis induced by neuromuscular blocking drugs during surgical anesthesia? Which drugs are preferred in this case?

1) Reverse the paralysis | 2) Neostigmine and edrophonium

What condition is characterized by increased intraocular pressure? AChE inhibitors can reduce intraocular pressure by? Therapy with AChE inhibitors has largely been replaced by?

1) Glaucoma 2) Stimulating mAChRs of the ciliary body and causing contraction, which facilitates outflow of aqueous humor 3) Topical β-blockers and prostaglandin derivatives

Patients with progressive dementia of the Alzheimer type are found to have a deficiency of? Donepezil, rivastigmine, galantamine, and physostigmine are AChE inhibitors that benefit patients with what condition?

1) Intact cholinergic neurons | 2) Dementia associated with Parkinson disease

Intoxication due to anticholinergic agents can produce cutaneous vasodilation, anhidrosis, anhidrotic hyperthermia, non reactive mydriasis, delirium, hallucinations, and a reduction of the desire to urinate which are all generally the result of? What can reverse the above mentioned anticholinergic effects? Why is it preferred?

1) Blocked mAChR stimulation 2) Physostigmine 3) It crosses the blood-brain barrier

Nondepolarizing neuromuscular blocking agents in combination with AChE inhibitors will cause diminished neuromuscular blockade however what is the one exception?

Mivacurium where neuromuscular blockade is prolonged

What drug in combination with AChE inhibitors will enhance phase 1 block and antagonize phase 2 block?

Succinylcholine

Cholinergic agonists act predominantly on?

mAChRs

What drug in combination with AChE inhibitors may enhance the bradycardic effects?

Beta-blockers

What drug in coadministration with AChE inhibitors may enhance muscle weakness seen in patients with myasthenia gravis?

Systemic corticosteroids

The SLUDGE symptoms of AChE intoxication are caused by stimulation of what receptor?

mAChR stimulation

What drug is the antidote recommended for cholinergic poisoning in combination with maintenance of vital signs (respiration in particular) and decontamination? Why is this the antidote?

1) Atropine | 2) It is a mAChR antagonist

Atropine is ineffective against what type of stimulation?

Peripheral neuromuscular stimulation (nAChRs)

Current antidotal therapy for organophosphate exposure resulting from warfare, terrorism, or other source includes?

1) Parenteral atropine 2) Pralidoxime 3) Benzodiazepine

Where do antinicotinic drugs elicit their effects at?

1) The neuromuscular junction | 2) nAChRs in the ganglia

What are often called parasympatholytic because they block the effects of parasympathetic autonomic discharge?

mAChR blockers

What is the prototype antimuscarinic compound?

Atropine

What type of amines such as Atropine, tropicamide, benztropine are used for their effects on the eye or CNS?

Tertiary amines

What type of amines such as Ipratropium and glycopyrrolate are charged and elicit their antimuscarinic effects in the periphery?

Quaternary amines

How do tertiary compounds and quaternary compounds compare to one another?

Tertiary compounds are more readily absorbed and widely distributed while Quaternary compounds are relatively free of CNS effects at low doses

What are the tissues most sensitive to atropine?

Bronchial, salivary and sweat glands

How does Atropine distinguish between mAChR types?

It doesn't because it antagonizes the actions of all 5 mAChRs

Although not as effective as dopaminergic therapy, tremor associated with Parkinson disease is reduced by? What are some examples?

1) mAChR antagonists | 2) Tertiary amines such as benztropine and trihexyphenidyl

Vestibular disturbances (motion sickness) appear to involve muscarinic cholinergic transmission and what is effective at prevention or reversal of these symptoms?

Scopolamine

Antimuscarinic agents have what effect on the eye?

1) Mydriasis (dilation) 2) Weak ciliary muscle contraction (poor near vision) 3) Reduced lacrimal secretion

Low doses of atropine result in what cardiovascular response? Moderate to high doses of atropine cause?

1) Initial bradycardia before the effects of peripheral vagal block manifest 2) Tachycardia by blockade of vagal slowing

Blockade of airway mAChRs can cause?

Bronchodilation and reduce secretion

Antimuscarinic agents have what effect on salivary secretion? What effect does inhibition of mAChRs have on gastric emptying time?

1) Decrease | 2) Prolonged

How are antimuscarinic agents useful in the treatment of urinary incontinence?

Relax smooth muscle of the ureters and bladder wall and slow voiding

What effect does Atropine have on thermoregulatory sweating? How does it do this? What can it cause in children?

1) Suppresses 2) Inhibits sympathetic cholinergic nerve fibers 3) Atropine fever

How is atropine used in surgical manipulation of visceral organs as an anesthetic? What is Atropine paired with to block parasympathetic effects during reversal of skeletal muscle relaxation?

1) Blocks vagal reflexes | 2) Neostigmine

What should antimuscarinic agents never be used for unless cycloplegia or prolonged action is required?

Mydriasis

What mAChR antagonists is used to prevent synechia formation in uveitis and iritis (the iris adheres to either the lens or the cornea)?

Homatropine

What is used as an inhalational agent in the treatment of asthma and COPD and is currently a first-line therapy?

Ipratropium

What recently approved agent has a longer bronchodilator action than ipratropium (half life 120 hrs vs. 2 hrs) and can be dosed once daily (vs. 3-4 times/day) in patients with COPD?

Tiotropium

What is the first drug of choice for symptomatic bradycardia in an advanced cardiac life support (ACLS) setting?

Atropine

The combination of atropine and diphenoxylate (trade name Lomotil) are used to treat?

Common traveler’s diarrhea

Agents with selectivity for what subtype of mAChR is preferred for agents that reduce urinary frequency due to presence in bladder wall and sphincter smooth muscle?

M3 subtype

Oxybutynin, Darifenacin, solifenacin, and tolterodine are all used in disorders of the genitourinary tract due it being selective for what mAChRs? Which one comes with side effects such as xerostomia and constipation?

1) M3 | 2) Oxybutynin

What is utilized to treat both CNS and peripheral effects of excessive stimulation of mAChRs due to cholinergic poisoning? What is a cholinesterase regenerator compound that can be used to treat organophosphate poisoning by breaking the bond between the organophosphate and cholinesterase enzyme?

1) Atropine | 2) Pralidoxime

Because Pralidoxime is charged it is only effective in regenerating cholinesterase at?

The neuromuscular junction

When is Atropine of no use in mushroom poisoning?

Delayed-onset

What may be adverse effects of antimuscarinic agents used to reduce GI secretion?

Mydriasis and cycloplegia

Moderate to high doses of atropine in children and infants can cause death due to? What is the treatment?

1) Hyperthermic effects | 2) AChE inhibitor

Antimuscarinic agents are contraindicated in patients with what condition? It should be used with caution in elderly men with a history of?

1) Glaucoma | 2) Prostatic hyperplasia

What should be avoided in patients with acid-peptic disease?

Non-selective antimuscarinic agents (atropine)

All ganglion-blocking drugs are?

Synthetic amines

What tertiary amine was developed from initial ganglion blockers and has improved GI tract absorption?

Mecamylamine

Ganglion-blocking agents competitively block the action of? Does it block either parasympathetic or sympathetic autonomic ganglia?

1) ACh and similar agonists at nAChRs | 2) Both, it blocks all autonomic outflow

Can mecamylamine cross the blood-brain barrier? Why or why not?

1) Yes | 2) It is uncharged

While the use of ganglion blockers is infrequent because more selective autonomic blocking agents are available, what is approved for use to treat hypertension?

Mecamylamine