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Pharmacology Block 1 > Cholinergics - Muscarinic Receptor Antagonists > Flashcards

Cholinergics - Muscarinic Receptor Antagonists Flashcards

1
Q

What is the general mechanism of a muscarinic receptor antagonist?

A

competitively block muscarinic receptors

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2
Q

What are 2 other names for muscarinic receptor antagonists?

A

Parasympatholytics

Antimuscarinics

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3
Q

What are the effects of muscarinic antagonists? (5)

A

Eye - Relax iris sphincter and cillary muscles -> mydriasis and paralysis of accommodation
Smooth muscle -> relax non vascular (airway, GI, urinary bladder)
Inhibit exocrine gland secretion
Heart - Increase heart rate
CNS - low dose -> sedation, high dose -> excitement, delerium, psychosis (toxic)

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4
Q

What is an alkaloid?

A

Naturally occurring plant derivative,

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5
Q

What are the uses of atropine?

A

Peptic ulcer disease
irritable bowel disease
spastic bladder
bradyarrhythmias (b/c of high vagal tone)

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6
Q

What are the current uses of atropine? (4)

A

Bradycardia during acute MI, and due to hyperactive carotid sinus reflex (high vagal tone)
Mydriasis and cycloplegia (paralysis of accommodation) -> treatment of acute inflammation in the eye ( iritis, choroiditis)
Anesthesia -> block vagal responses
AChE or muscarinic toxicity

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7
Q

What was the ancient Italian use of atropine?

A

Produce mydriasis (dilation) for beauty

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8
Q

What is the duration of action of atropine?

A

LONG (7-10 days)

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9
Q

Why is atropine no longer used to treat other ailments?

A

Too many side effects

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10
Q

What is the major therapeutic use of Scopolamine?

A

motion sickness -> decrease nausea

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11
Q

What is the route of administration of Scopolamine and what makes this possible?

A

Transdermal patch -> lipophillic, can penetrate CNS and skin

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12
Q

What are the 2 naturally occurring alkaloids?

A

Atropine and Scopolamine

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13
Q

What drug is a semi-symthetic derivative of an alkaloid?

A

Ipratropium

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14
Q

What are the major therapeutic uses of Ipratropium?

A

COPD

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15
Q

What is the route of administration of Ipratropium?

A

inhalation

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16
Q

What is significant about the structure of ipratropium?

A

Quaternary ammonium -> (+) -> no CNS penetration and poor systemic absorption when inhaled

17
Q

What are the effects of ipratropium?

A

reduce bronchial secretions and reduce bronchial constrictions

18
Q

What is a second approved use for Ipratropium?

A

nasal inhalers for treatment of rhinorrhea -> due to common cold or rhinitis

19
Q

What are the 4 synthetic antagonists?

A

Tropicamide
Oxybutynin
Darifenacin
Glycopyrrolate

20
Q

Tropicamide

1) Duration of action/onset
2) Therapeutic use/effects

A 
Fast onset (20-40 minutes), Short duration (4-6h)
Used to produce mydriasis, cycloplegia (eye exams) ->dilation
21
Q

Oxybutynin

1) Therapeutic uses
2) Side Effects

A

1) Overactive bladder and incontinence -> decreases parasympathetic action causing constriction of urinary muscles
2) High incidence of side effects -> untolerable
drowsiness, confusion, blurred vision, constipation, xerostomia

22
Q

Darifenacin

1) Why unique
2) Therapeutic uses
3) Why preferred

A

1) M3 selective muscarinic antagonist
2) overactive bladder, incontinence
3) M3 receptors on bladder/muscles involved in urination -> fewer CNS side effects

23
Q

Glycopyrrolate

1) Therapeutic uses
2) Structure significance

A

1) block parasympathomimetic effects during reversal of neuromuscular blockade with AChE agents
2) + amine so no CNS penetration

24
Q

What are the side effects of muscarinic antagonists (5) Low dose

A
  1. hot as a hare (no sweating)
  2. dry as a bone (dry mouth, dry hot skin, no sweating)
  3. red as a beet (b/c heat and no sweat)
  4. blind as a bat (b/c no accommodation)
  5. drowsiness (CNS)
25
Q

What are the side effects of muscarinic antagonists at high doses (toxic)?

A

All of low dose + mad as a matter (ataxia, restlessness, excitement, hallucinations, delirium, coma)

26
Q

What condisitons should be taken into consideration with muscarinic antagonists?

A

glaucoma - b/c could increase intraocular pressure
prostatic hypertrophy - could increase difficulty voiding
any disease with tachycardia

27
Q

How do you treat muscarinic antagonist poisoning?

A

physostigmine

limit absorption if taken orally

Pharmacology Block 1 (8 decks)

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