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Pharmacology Drug Flashcards > Pharm 2013.09.05 Cholinergic 1 > Flashcards

Pharm 2013.09.05 Cholinergic 1 Flashcards

1
Q

Describe the major differences among the cholinergic receptor subtypes

Explain the uses and side effects of muscarinic blocking drugs

List the differences between depolarizing and non-depolarizing blockers of NMJ

Describe one ganglionic blocking drug

Explain the uses and pharmacology of botulinum toxin (Botox)®

A

…

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2
Q

What are the non-specific anticholinergics?

A

no direct acting

Botulism (indirect acting)

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3
Q

What are the specific Muscarinic Antagonists ?

A

Atropine
Scopolamine
Others

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4
Q

What are the DEPOLARIZING Nm Antagonists?

A

Succinylcholine

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5
Q

What are the NON-DEPOLARIZING Nm Antagonists?

A

d-Tubocurarine
Aminosteroids (pancuronium, vercuronium, Rocuronium)
Benzylisoquinolines (Cisatracurium, d-Tubocurarine)

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6
Q

What is the Nn blocker (ganglionic blocker)?

A

Trimethaphan

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7
Q

What are the types of Muscarinic receptors?

Are anticholinergics specific to the different types?

A

Anticholinergics are not specific to subtypes of Muscarinic receptors.
The following list is for reference only.

G-protein coupled receptors (GPRCs)
5 major types (M1 – M5)
M3 in most tissues 
M2 in heart
M1 in gastric parietal cells
M4 & M5 in CNS
M1, M3, M5 use Gq (odd ones are queer)
Gq (Queer) stimulates phospholipase C
** Leads to elevated Ca+2
 M2, M4 (uses Gi)
** Gi Inhibits adenylyl cyclase
** Activates K+ channels
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8
Q

What are the typs of Nicotinic receptors

This is for the USMLE only.

A 
Ligand-gated Na+/K+ channels
Pentamer of several possible subunits
** 10 a types (a1-a10)
** 4 b types (b1-b4)
** 1 d subunit
** 1 g subunit
** 2 major types
NM (muscle) in skeletal muscle (NMJ) 
** Predominantly (a1)2b1dg
NN (neuronal) in autonomic ganglia & CNS
**12 different types
** Different combinations of a and b
** Never a1 or b1
** Ganglionic is a3a5(b2)3
** Chantix™ is selective for (a2)2(b4)3 neuronal receptors
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9
Q

In general, what are the effects of Muscarinic blockers?

A

Parasympatholytic

Effects organs, sweat glands, and CNS

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10
Q

Through what muscarinic blockers work?

A

competivite inhibitor

shifts the receptor to an inactive form

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11
Q

In terms of muscarinic antagonists, what is the difference between tertiary and quaternary amine forms?

A

Tertiary is uncharged and affects CNS and PNS

Quaternary is charged and affects PNS

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12
Q

What are the specific Muscarinic Antagonists ?

A

Atropine
Scopolamine
Others

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13
Q

Note: Drug-Receptor sensitivity does not equal potency.

What is an example?

A

Atropine sensitivity highest in salivary, bronchial, and sweat glands
Atropine potency highest in heart, bronchial and GI muscle

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14
Q

Atropine is the example drug of antimuscarinic.

A

…

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15
Q

What are the effects of Atropine?

A

1) Anti-DUMBBELSS
2) Mad as a Hatter: Delirium
3) Blind as a Bat: Mydriasis (pupil dilation), Photophobia, Cycloplegia (blurred vision), and exacerbation of angle glaucoma
4) Dryness: dry mouth, dry skin, dry eyes, decreased broncho secretions
5) Hot as a hare: Temperature (most dangerous to pediatrics), tylenol does not remedy, requires ice cooling
6) Red as a beet
7) Pee Pee dance: block detrusor muscle causes urinary retention that may need catheterization

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16
Q

Atropine is sometimes used for surgery to keep secretions low

A

…

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17
Q

Atropine toxicity?

A

Adults: no toxicity, but psychiatric symptoms are biggest concern
Children: fever toxicity, give ice baths

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18
Q

What are the effects of Atropine on
Bronchi?
GI?
Cardiovascular?

A

Bronchi: dilation, blocks smooth muscle constriction
** may be used for Asthma and COPD
GI: Constipation and blocks GI motility
** may be used for irritable bowel syndrome
CV: Tachycardia and hypertension
** may be used for bradycardia

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19
Q 
What is Scopolamine?
What is it used for?
What is the mechanism in the CNS?
What is the administration route?
What are the side effects?
A

1) Scopolamine is a specific muscarinic antagonist
2) Used for motion sickness and for anesthesthia as an adjunct to reduce amnesia and bronchosecretions
3) Unknown CNS mechanism
4) Transdermal patch for motion sickness
5) Standard Atropine effects (mad hatter, dry as a bone, impaired near vision

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20
Q 
What muscarinic antagonists are used for
Surgery adjunct (2)?
Motion sickness (1)?
Irritable bowels and minor diarrhea (2)?
Peptic ulcer (3)? (USMLE only)
Genitourinary urgency (2)? (USMLE only)
A 
Surg: Atropine and Scopolamine
Mot: Scopolamine
GI: Atropine and Dicyclomine
Ulcer: Methscopolamine, Pirenzepine, Propantheline
GU: Oxybutynin, Glycopyrrolate
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21
Q

What is Dicyclomine?
What are its administration?
What is the half life?

A

Muscarinic antagonist used for GI, Irritable Bowel and minor Diarrhea
Oral or IM administration
Short Half Life, but effects last for 6 hours

22
Q

USMLE: What Muscarinic antagonists are used in opthalmology?
For retinal exam?
For post-surgery prevention of Synechiae?

A

Opthalmology – Mydriatic eye drops

1) For retinal examation
* * Tropicamide: shortest duration of action (15 - 60 min)
* * Multiple other agents including scopolamine & atropine
2) Post surgical prevention of synechiae
* * Adhesion of the iris to the cornea or lens
* * Atropine: duration 5 – 6 days
* * Homatropine: duration 12-24 h

23
Q

What Muscarinic Antagonist is used for Parkinson’s disease?

A

Benztropine

24
Q

What muscarinic antagonists are used for Respiratory illnesses, such as asthma and COPD?

A

Ipratroprium

Tiotropium

25
Q 
What is Iproatropium?
What illness is it used for?
What is administration?
What is its CNS penetration?
What does it do?
What drug is it packaged with?
A

Anticholinergics are first line therapy in persistent COPD
Aerosol delivery
Quaternary amine, low CNS penetration, low systemic absorption
Inhibits bronchoconstriction
Also packaged with albuterol (b2-agonist) for asthma
Note: TID - QID

26
Q

What is Tiotropium and how does it compare to Ipratropium?

A

Similar to Ipratropium, but longer acting

Note: QD

27
Q

What drugs are used for cholinergic poisoning?

What about organophosphate poisoning?

A

Chol: Atropine with I.V administration
Org: Pralidoxime

28
Q

What are the general differences between Nm blockers and Nn blockers?

A

Nm block at the NMJ; Nn block at the Ganglion

Nm blocker side effects: ganglionic and CNS blockade: Nn blocker side effects: NMJ blockade or CNS

29
Q

What is the only useful Nn blocker?

A

Trimethaphan

30
Q

What is the only use of Nm blockers?

A

inhibit muscular activity during surgery

31
Q

Review: What are the actions of Nicotinic overactivation?

A

Initial activation → subsequent deactivation
Initial depolarization leads to muscle fasciculations
depolarization-desensitization blockade)
Result is a paradoxical flaccid paralysis which cannot be practically reversed; have to wait until agonist is cleared
Over activation of the nicotinic receptor produces a net K+ efflux from muscle → hyperkalemia and arrhythmia
Only 1 useful agent: succinylcholine

32
Q

What is the only depolarizing nicotinic NMJ blocker?

A

Succinylcholine

33
Q

What are the features of Succinylcholine?
When is it used?
How selective for NMJ?
What is administration and dosage routes (2)?
How is it cleared from the body?
Which muscles are effected first?

A

Dimer of ACh
Used for short surgical procedures
Semi-Selective of NMJ
I.V. controlled drip titrated to desired muscular relaxation OR
I.V. single large dose for rapid onset and short duration
Cleared with AChE
Large muscles first: chest, abdomen, neck, and legs

34
Q

What are the adverse effects of Succinylcholine?

A

1) Paralyzation in patients without AChE
2) Muscle fasciculations → post surgical pain
3) Hyperkalemia
4) Histamine release
* * Warmth, vasodilatation
5) Malignant hyperthermia (very rare)

35
Q

Detail: What are the mechanisms of succinylcholine in production of malignant hyperthermia?

A

Involves halogenated inhalation anesthetics
** Especially halothane
Massive release of Ca++ from the sarcoplasmic reticulum
Muscle ridgidity
Mutant ryanodine receptor (SR calcium channel)
Uncontrolled increase in skeletal muscle oxidative metabolism
↓ pO2,  pCO2 (acidosis),  temperature, muscle ridgidity

36
Q

What are the Rx for succinylcholine malignant hyperthermia?

A

Rx: O2, bicabonate, ice baths, hyperventilation,
Rx: dantrolene (blocks the ryanodine receptor)

37
Q

What are the contraindications for succinylcholine?

A 
Family Hx of malignant hyperthermia
Hyperkalemia
Burns, trauma, tissue injury
** Severe hyperkalemia → cardiac arrest
Heart failure
** arrhythmias
38
Q

In one sentence, how does succinylcholine work?

A

Overstimulation of Nm to depolarize the receptor and cell.

Note the rest of the Nicotinic receptors are non-depolarizing

39
Q 
What is the prototypic Non-Depolarizing Nicotinic NMJ blocker?
What are its features?
How long does it work?
Which muscles are effected first?
How do you reverse effects?
A 
d-Tuborurarine
Quaternary amine  (minimal CNS effects)
Rapid onset (IV)
** Relaxation for intubation: 90 – 120 s
** Relaxation for surgery:  2 - 4 min
Full recovery from paralysis 1 – 3 hr
Small muscles affected before large (opposite to succinylcholine)
Effects reversed rapidly with neostigmine
40
Q

For nondepolarizing nicotinic blockers (competitive inhibitors) what do you reverse with?

For depolarizing nicotinic blockers (succinylcholine) what do you reverse with?

A

Non-dep: Neostygmine (it is charged, so only PNS)

Dep: allow AChE to clear succinylcholine. Do NOT use neostygmine, lest you produce muscurinic syndrome

41
Q 
Compare Neostygmine (depolarizing) and Non-depolarizing Nicotinic NMJ antagonists in terms of which and when muscles are paralyzed?
What about how long the surgery?
A

Neo: Large muscles first and short surgery

d-Tuborurarine and non-depol: small muscles first and long surgery

42
Q

What are the side effects of non-depolarizing nicotonic NMJ antagonists?

A

Tachycardia
Hypertension
Histamine release
Ganglionic and muscarinic side effects

43
Q

What are the Aminosteroids non-depolarizing nicotinic NMJ antagonists (3)?
What organ metabolizes each drug for clearance?

A

Pancuronium (Renal clearance)
Vecuronium (Hepatic clearance)
Rocuronium (Hepatic clearance)

44
Q

What is the Benzylisoquinoline non-depolarizing nicotinic NMJ antagonist?

A

Cisatracurium (inactivated by Plasma AChE)

45
Q 
Which non-depolarizing nicotinic NMJ  antagonist agent would you use in the following patients?
Renal disease?
Liver disease?
Renal and Liver Disease?
Plasma AChE deficiency?
A

Renal disease → not Pancuronium
Liver disease → not Vecuronium or Rocuronium
Renal and liver disease → Cisatracurium
Plasma ChE deficiency → not Cisatracurium

46
Q

What is the Nn blocker (ganglionic blocker)?

A

Trimethaphan

47
Q 
What is Trimethaphan?
Does it affect CNS or PNS?
What does it do?
What is the administration?
Cleared by LV or KD?
A

1) A sulfonium compound (permanent positive charge)
* * minimal CNS effects
2) Blocks all ganglia, but is used for its effects on sympathetic ganglia
* * Extremely potent effects on blood pressure
* * BP is predominantly controlled by sympathetic system
3) Given IV, rapid onset
4) Rapidly cleared by liver (minutes)

48
Q

What are side effects of Teimethaphan?

When is it used?

A

1) Orthostatic hypotension
2) Urinary retention, constipation, impaired accommodation of lens of the eye
3) Only used in emergency situations
* * Hypertensive crises
* * Dissecting aortic aneurysm

49
Q

What is an Indirect Anticholinergic?

A

Botox

50
Q

What is the mechanism of Botulism?

A

1) Normal docking of synaptic vesicles
* * SNARE proteins are on neurotransmitter vesicles and cell membrane docking sites
* * Docking requires binding of cell membrane and vesicle SNARE proteins
* * ACh is released
2) Toxin A mechanism of action
* * Binds receptors and is endocytosed
* * Light chain escapes from vesicles
* * Light chain cleaves SNARES so no docking

51
Q

What are applications of Botox?

A

Cosmetic
Look mom, no more wrinkles!!!
Prevent axillary hyperhydrosis (arm pit sweating)
Strabismus (unaligned eyes)
Blepharospasm (uncontrolled eyelid twitching)
Spasmodic torticollis
neurologic disorder causing irratic head movements
Anal achalasia to heal fissures

Pharmacology Drug Flashcards (4 decks)

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