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pda 1 > cholinergics > Flashcards

cholinergics Flashcards

1
Q

Muscarinic receptor agonists (parasympathomimetics)

A

direct agonists of muscarinic receptors

produce effects similar to those observed during stimulation of post ganglionic parasympathetic nerves

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2
Q

Muscarinic receptor antagonists (parasympathlytics, antimuscarinic agents)

A

completely block muscarinic receptors, interfere with responses that result from parasympathetics stimulation

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3
Q

Acetylcholinesterase inhibitors (Anticholinesterase

A

agents that enhance the effects of endogenously produced Ach by blocking its natural breakdown by the enzyme acetylcholinesterase
effective at any site where Ach is the NT

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4
Q

Ganglionic blocking agents

A

neural nicotinic receptor antagonist

competitve antagonists for nicotinic receptors at autonomic ganglia

interfere with ganglionic transmission of both parasympathetic and sympathetic nerves

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5
Q

where are muscarinic receptors located

A

autonomic effector cells innervated by post gang Parasymp

also located on some cells that have no cholinergic innervation (vascular endothelial cells)

located within CNS

actions are blocked by atropine

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6
Q

properties and subtypes of muscarinic receptors

A

5 subtypes (all are GPCRs), widely distributed most cells express a few subtypes but one usually predominates

M2s: functionally dominant subtype in heart
M3s: functionally dominant subtype in smooth muscle, secretory glands, eyes and vascular endothelium

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7
Q

effects of muscarinic receptor activation on CV, pulm, UT, GI, misc peripheral effects, CNS effects

A

CV: Vasodilation (M3 endothelial, M2 decrease HR, M2 decrease AV node)

pulm: bronchoconstriction M3, tracheobronchial secretion M3

UT: detruser muscle contraction M3

GI: increased tone, amp contractions, secretion M3

misc peripheral effects: increase secretion glands M3, miosis and accommodation M3

CNS effects: cortical arousal, all 5 receptors

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8
Q

Choline esters

A

bethanechol, resistant to hydrolysis by cholinesterases, thus T1/2 is increased compared to Ach

Quaternary amines, low F, does not cross BBB

non-selective

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9
Q

Naturally occuring alkaloids

A

pilocarpine is a tertiary amine, therefore readily absorbed after oral admin penetrates CNS

non selective

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10
Q

Bethanecole

A

primary effect: on UT and GI tracts

orally or subQ for urinary retention (post op, diabetic neuropathy, hypoactive bladder)

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11
Q

Pilocarpine

A

used for treatment of xerostomia (due to head and neck radiation Sjörgren syndrome)

Topically in opthalmology for treatment of glaucoma and as mitotic agent

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12
Q

side effects and contraindications of muscarinic receptor activations

A

common side effects: diaphoresis, diarrhea, nausea, difficulty with accommodation, and hypotension
contraindications: asthma and COPD, UT or GI obstruction, acid peptic disease, CV disease accompanied by brady cardia or hypotenstion

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13
Q

Toxicology of muscarinic agonists (parasympathomimetics, pilocarpine, bethanecole)

A

poisoning by ingestion of muscarinic agonists:
SLUDGE (salivation, lacrimation, urination, defecation, gastrointestinal upset, emesis) also hypertension, and bradycardia, and difficulty with accommodation

reversal with atropine

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14
Q

muscarinic receptor antagonists (parasympatholytics, or antimuscarinics) and their effects (CV, resp, eye, GI, smooth muscle, sweat glands, CNS)

A

competitve inhibitors of muscarinic receptors

CV- tachycardia, Av nodal conduction (M2), block reflex vagal slowing of HR and AV node, no effect on vascular tone or BP

Resp- bronchodilation, dec. tracheobronchial secretions (M3 receptor), dries mucous membranes of resp tract

eyes- dilate pupils (mydriasis) and paralyze accommodation by blocking cholinergic response of the pupillary sphincter muscle and ciliary muscle (M3 - photophbia)

GI: decrease secretions, decrease motility (M3)

sm muscl: decrease in tone of ureter and bladder (M3)

sw gland: inhibit activity of sweat, increases body temp

CNs: depression and drowsiness

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15
Q

naturally occuring alkaloids of muscarinic antagonist

A

from belladonna plants (atropine, and scopolamine)

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16
Q

semisynthetic of muscarinic antagonist

A

ipratropium

17
Q

synthetics of muscarinic antagonist

A

tropicamide, oxybutynin, darifenacin, glycopyrrolate

18
Q

atropine

A

prototypical antagonist
non-subtype selective muscarinic receptor antagonistss, absorbed orally by the GI tract
Therapeutic uses: bradyarrythmias due to high vagal tone
ophthalmic uses (to produce mydriasis and cycloplegia/paralysis of accommodation)
long acting, treats chronic inflammatory disorders
uses during anesthesia (blocks responses to vagal reflexes and reduces tracheobronchial secretions)

anticholinesterase or muscarinic toxicity

19
Q

scopolamine

A

non-subtype selective muscarinic receptro antagonist,

greater CNS penetration

major use is to treat motion sickness and vestibular disease

available as a transdermal patch

20
Q

ipratropium

A

non-subtype selective muscarinic receptor antagonist

Quaternary ammonium compund used exclusively for respiratory tract (inhalation)

COPD

reduces bronchosecretions and alleviates bronchoconstriction

21
Q

tropicamide

A

opthalmic solution to produce mydriasis and cycloplegia

fast acting and short duration

22
Q

oxybutynin

A

Urinary incontinence

high incedents of antimuscarinic side effects

23
Q

darifenacin

A

urinary incontinence
M3 receptors
less CNS side effects than oxybutinin

24
Q

glycopyrrolate

A

blocks parasympathomimetic effects during reversal of NMJ blockade with anti cholinesterase agents

quaternary amine-> no CNS penetration

25
Q

side effects of muscarinic antagonists, contraindications and toxicity

A

xerostomia, blurred vision, dyspepsia, constipation, cognitive impairment

contraindications: urniary or GI tract obstruction, uncontrolled glaucoma, benign prostatic hyperplasia, conditions worsened by tachycardia
toxicology: belladonna alkaloids, Hot as hare (no sweating), dry as a bone (dry mouth), red as a beet (excessive heat), blind as a bat (mydriasis), mad as a hatter (ataxia etc)

treat with physostigmine

26
Q

acetylcholinesterase inhibitors

A

cause an increase in acetylcholine in the vicinity of cholinergic nerve terminals

aka anticholinesterase agents

insecticides, pesticides, nerve gases

loci: where Ach is released: muscarinic receptors, autonomic ganglia, CNS

therapeutic uses for: atony of smooth muscle of GIT, UT, glaucoma, mg, reversal of competitve NMJ blocking drugs

27
Q

enzymatic hydrolysis of Acetylcholine

A

transiently acetylated at numerous loci on the enzyme

28
Q

non covalent (reverisble) inhibitors of AchE

A

Edrophonium: quaternary ammonium (no CNS activity), must be IV administered, rapid onset and short durations

Used for diagnosis of MG, and the reversal of paralysis by competitive NM blocking drugs

29
Q

Reversible carbamate inhibitors of AchE

A

hydrolyzed by AchE but at a slow rate

Physostigmine: alkaloid from calabar bean, slowly reversible (hrs) tertiary amine (has CNS effects)

uses treatment of chronic wide angle glaucoma, treats toxicity of CNS antimuscarinic agents)

Neostigmine: slow reversible, quat amine no CNS effects), treatment of MG oral, preventation and treatment of post op atony of gut and bladder, reversal of paralysis by competitive NMJ blocking drugs

30
Q

organophosphorus compounds

A

phosphorylate the AchE, return of the activity depends on synthesis of new enzymes, lipophilic and penetrate CNS

Nerve gases: sarin
Insecticides: malathion (rapidly detoxed in higher order organisms)

toxicity: SLUDGE +hypotension+bradycardia+difficiuly with eyes

reduced respiration, muscle paralysis, death

antidotes: atropine and with moderate to severe pralidoximine (reactivates AchE, but not effective with aged)

31
Q

ganglionic blocking drugs

A

Ach is released from parasympathetics and sympathetic pre ganglionic neurons, activates postganglionic nicotinic receptors (cation influx)

neural nicotinic receptor antagonist - specifically block both the parasympathetic and sympathetic systems

leads to vasodilation

32
Q

competitive neuromuscular blocking agents

A

aka non-depolarizing drugs
antagonists of nicotinic receptors at the neuromuscular junction (Nm)
duration of action: short, medium, long duration
side effects: Nn receptor blockade, M receptor blockade, releaase of histamine
route of elimination: inactivated by metabolism or removed by renal excretion

33
Q

Rocuronium

A

intermediate duration of action, but rapid onset of action, can be used to facilitate endotracheal intubation, hepatic elimination, no Nn/receptor blocking or histamine releaseing effects
also cisatracurium, vecuronium, pancuronium (long)

34
Q

depolarizing neuromuscular blockers

A

activate nicotinic receptors at NMJ maintinging motor end plate depolarization

Succinylcholine: has a quat ammonium, does not enter the CNS, not orally absorbed, allows tracheal intubation (rapid onset, short duration of action

metabolized by pseudocholinesterase

35
Q

side/adverse effects of nmj block

A

prolonged apnea, CV collapse (due to histamine release anaphylaxis)

Malignant hyperthermia (succinylcholine)
hyperkalemia

toxic effects: (respiratory paralysis, treat with positive pressure, neostigmine.edrophonium) +glycopyrrolate

pda 1 (11 decks)

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