Cholinergic Antagonists Flashcards by Suzanne Zick

What is an agonist?

Molecule found in nature/made in lab

binds to specific receptor –> elicit same response as endogenous compound would when bound

How well did you know this?

Not at all

Perfectly

What is an antagonist?

Molecule found in nature/made in lab

incompletely binds to specific receptor

blocks usual response from occurring

can also observe opposite response –> dry mouth instead of salivation

How well did you know this?

Not at all

Perfectly

Can the dose amount of agonist/antagonist alter observed effects? If so why?

Yes

higher doses can engage in more receptors or more receptor types –> exaggerated response + signs of toxicity (more pathways triggered)

How well did you know this?

Not at all

Perfectly

What are the 2 types of Cholinergic antagonists?

Muscarinic Antagonists

Nicotinic Antagonists

How well did you know this?

Not at all

Perfectly

What is another name for a cholinergic antagonist?

Anticholinergic

How well did you know this?

Not at all

Perfectly

What is another name for a muscarinic antagonist?

parasympatholytic

antimuscarinic

How well did you know this?

Not at all

Perfectly

What does a muscarinic antagonist do?

Block effects of parasympathetic autonomic discharge

How well did you know this?

Not at all

Perfectly

What are 2 examples of muscarinic antagonists?

Atropine

Scopolamine

How well did you know this?

Not at all

Perfectly

What are the 2 types of nicotinic antagonists and what do they do?

Ganglionic Blockers - block ALL outflow past ganglionic level

Neuromuscular Blockers - prevent skeletal muscles from working properly

How well did you know this?

Not at all

Perfectly

What are some examples of Nicotinic Antagonists?

Tetraethylammonium

Tubocurarine

Succinylcholine

How well did you know this?

Not at all

Perfectly

What is another name for Atropine?

Hyoscyamine

How well did you know this?

Not at all

Perfectly

Where does atropine come from?

Origianally isolated from plants –> Atropa belladonna

Derivatives synthesized in lab

How well did you know this?

Not at all

Perfectly

What is atropine?

classic cholinergic antagonist

How well did you know this?

Not at all

Perfectly

What are some other drugs that have similar structures and produce similar effects as Atropine?

Antihistamines

Phenothiazine antipsychotics

Tricyclic antidepressants

How well did you know this?

Not at all

Perfectly

What are the actions of atropine?

Resversible block muscarinic receptors –> prevents ACh from binding to those sites

How well did you know this?

Not at all

Perfectly

Will Atropine block actions of exogenously administered cholinergics or endogenous acetylcholine?

Typically blocks actions of EXOGENOUSLY administered cholinergics

How well did you know this?

Not at all

Perfectly

Which tissues are most sensitive to Atropine?

Salivary

Bronchial

Sweat glands

How well did you know this?

Not at all

Perfectly

What other tissues are effected by Atropine?

Eye

CV system

GI tract

GU tract

CNS

How well did you know this?

Not at all

Perfectly

What are the CNS effects of anticholinergics and why do they produce those effects?

Atropine –> minimal CNS effect; can’t cross BBB

Scapolamine –> drowsiness/amnesia; can cross BBB

How well did you know this?

Not at all

Perfectly

What are some signs of scopolamine toxicity?

CNS excitement

CNS agitation

hallucinations

coma

How well did you know this?

Not at all

Perfectly

Which antimuscarinic is used in Parkinson’s and what is it treating?

Benztropine

treat tremors

How well did you know this?

Not at all

Perfectly

Why would you use antimuscarinics to treat Parkinson’s?

In parkinson’s there is to much ACh

Benztropine will block ACh effects

How well did you know this?

Not at all

Perfectly

How would you treat motion sickness and how would you administer the drug?

Scopolamine patches

Injection, orally, transdermal patch

How well did you know this?

Not at all

Perfectly

What are the effects of Antimuscarinics on the Eye?

block cholinergic stimulation of pupillary constrictor muscle –> mydriasis (unopposed sympathetic dilation)

prevent contraction of ciliary muscle –> cycloplegia (loss of accommodation) –> unfocused near vision –> blurry vision

Reduce lacrimal secretion –> dry eye

can DANGEROUSLY worsen narrow angle glaucoma (lack of outflow of aqueous humor)

How well did you know this?

Not at all

Perfectly

What are the therapeutic uses of antimuscarnics on the eye?

used for opthamologists to view the retina --> mydriasis and cycloplegia = good in this case But not commonly used anymore

How are antimuscarnics administered in the eye?

Drops Ointment

What are the low does effects of antimuscarinics ( .5 mg atropine) on the cardiovascular system?

atropine block M1 receptors only --> bradychardia; ACh still can bind to M3

What are the effects of moderate to high doses of antimuscarinics (1-5 mg atropine) on the cardiovascular system?

block M2 receptors in SA/AV nodes that USUALLY slow HR --> tachycardia **like inhibiting brakes on HR**

What are the effects of toxic doses of antimuscarinics (>10 mg atropine) on the cardiovascular system?

intraventricular condition block --> inhibits electrical pulse generation in pacemaker nodes

Why does antimuscarinics (atropine) have little effect on BP?

There are minimal innervations from parasympathetic system

What are the therapeutic uses of antimuscarinics (atropine) in CV disorders?

During acute MI or SA/AV node function --> bradycardia; so you want to give moderate dose of antimuscarinic (atropine) --> block M2 receptors --> increase HR

What are the effects of anticholinergics on the Respiratory System?

Bronchodilation --> better air flow Reduce/dry-up secretion

What are some anticholinergic drugs used for respiratory disorders and how are they given?

Ipratropium (Atrovent) and Tiotropium (Spiriva) given as inhaler or nebulizer --> bronchodilation

What are Ipratropium (Atrovent) and Tiotropium (Spiriva) used to treat?

Asthma COPD

What are some other uses of atropine or scopolamine regarding the respiratory system?

Dry upper/lower respiratory secretions prior to surgery or in mechanically vented patients

What are the effects of antimuscarinics on the GI tract?

reduced motility --> prolong gastric emptying time/slowing intestinal transit time reduce salivary secretion --> dry mouth (common side effect) reduce gastrointestinal secretions

What are some therapeutic uses of atropine in GI disorders?

reducing GI secretions (BUT NOT ACID IN STOMACHE) treat diarrhea

What is Lomotil and what is it used for?

Diphenoxylate + atropine slow down gut motility --> treat somache bugs

What are the effects of Antimuscarinics on the GU tract?

relaxation of smooth muscle in ureter/bladder wall --> reduces voiding

Why wouldn't you want to give an antimuscarinic to a pt with benign prostatic hyperplasia (BPH)?

can worsen or causes urinary retention

What are some therapeutic uses of anticholinergics in urinary disorders?

urinary tract spasms associated w/ inflammation, surgery, or neurologic conditions **incontinence**

What is the classic anticholinergic used to treat urinary disorders?

Oxybutinin

How would you treat muscarinic toxicity?

anticholinergics! Atropine 2-PAM (pralidoxime)

How would you most likely get mushroom poisoning?

Eating wild mushrooms --> contain natural cholinergic agents

What are the 2 types of mushroom poisoning?

Rapid onset Delayed onset

Describe rapid onset mushroom poisoning and how you would treat it?

Occurs w/ in 15 - 30 minutes after ingestion muscarinic side effects treat w/ atropine

Describe delayed onset mushroom poisoning and how would you treat it?

Occurs 6 - 12 hours after ingestions muscarinic side effects + renal/hepatic toxicity treat w/ supportive care (atropine = ineffective)

What type of sweat gland problem can be treated with muscarinic antagonists?

eccrine hyperhidrosis

What is the name of the drug that could be used to treat eccrine hyperhidrosis?

Glycopyrrolate

What are some adverse side effects of anticholinergics?

Dry mouth (dry as a bone) Mydriasis (blind as a bat) Tachycardia Hot, Flushed skin (red as a beet) Agitation (mad as a hatter) Urinary retention (can't pee) Visual changes (can't see) Constipation (can't shit)

What are some drugs that produce anticholinergic side effects?

TCAs Antihistamines Phenothiazine antipsychotics

What are 3 contraindications of anticholinergic use?

Gluacoma (especially narrow angle) Elderly men with BPH (benign prostatic hyperplasia) Gastric Ulcers

Why would glaucoma be a contraindication for anticholinergics?

anticholinergics cause angle closure --> prevent outflow of aqueous humor

Why is BPH a contraindication for anticholinergics?

can worsen or causes urinary retention

Why are gastric ulcers a contraindication for anticholinergics?

anticholinergics --> slowed gastric emptying --> aggregate ulcer symptoms

What does the toxin from clostridium botulinum do?

targets presynaptic proteins that block release of ACh

What is the result of the toxin from clostridium botulinum?

paralysis of skeletal muscle decreased activity @ parasympathetic and sympathetic synapses inhibition can last weeks --> months

What is the toxin from clostridium botulinum used to treat?

blepharospasm other focal muscle spasms hyperhidrosis of palsm/axillae cosmetic removal of wrinkles

What do ganglionic blocking agents do?

block ACh (and agonists) @ nicotinic receptors of parasympathetic/sympathetic ganglia

What is another name for ganglionic blocking agents?

Nondepolarizing competitive antagonists

What are some ganglionic blocking agents?

Tetraethylammonium (TEA) Hexamethonium (C6) Mecamylamine Trimethaphan

What kinds of effects of ganglionic blockers (sympathetic or parasympathetic)?

Mixed sympathetic/parasympathetic effects

What are some of the CNS effects of ganglionic blockers?

Sedation Tremor Choreiform movements Mental aberrations

What are some of the ganglionic blocker effects on the eye?

Cycloplegia = Loss of accommodation Moderate dilation of pupil

What are some of the ganglionic blocker effects on the CV system?

Tachycardia

What are some of the ganglionic blocker effects on the GI tract?

decrease secretions decrease motility

What are the therapeutic uses of ganglionic blockers?

Really only used in pharmacological research

What do neuromuscular blockers do?

@ synapse block neuromuscular transmission between motor end plate and nicotinic receptors on skeletal muscle

What are the 2 groups of neuromuscular blockers?

Nondepolarizing (antagonists) Depolarizing (agonists)

What do non depolarizing neuromuscular blockers do?

block ACh from binding nicotinic receptors prevent depolarization of muscle fibers and inhibit contraction result in very relaxed (paralyzed) muscle

Do nondepolarizing neuromuscular blockers bind competitively or noncompetitivelly?

competitively

How can you terminate the effect of non depolarizing neuromuscular blockers?

AChE inhibitors will increase ACh and overcome the competition for blocked receptors

When are non depolarizing neuromuscular blockers used?

during surgery --> muscle paralysis (relaxation) ICU

How do non depolarizing neuromuscular blockers differ from each other?

differ by onset of action, half-life, means of elimination

What is a classic example of depolarizing neuromuscular blocker?

Succinylcholine

What does depolarizing neuromuscular blockers do?

binds to nicotinic receptors on skeletal muscle acts like ACh proivdes constant stimulation of receptor Initially cause depolarization Continued presence prevents transmission of further impulses causes resistance to further depolarization --> paralysis

What are 2 advantages of depolarizing neuromuscular blockers?

rapid onset short duration of action **give same effect as non polarizing antagonist**

What are the therapeutic uses of depolarizing neuromuscular blockers like succinylcholine?

Facilitate intubation electroconvulsive shock therapy